# Old Frisian

Old Frisian was a West Germanic language spoken between the late 13th century and the end of 16th century. It is the common ancestor of all the modern Frisian languages except for the Insular North Frisian dialects, with which Old Frisian shares a common ancestor called Pre–Old Frisian or Proto-Frisian. Old Frisian was spoken by contemporary Frisians who comprised a loose confederacy along the North Sea coast from around modern-day Bruges in Belgium to the Weser in modern-day northern Germany, dominating maritime trade. The vast majority of the surviving literature comprises legal documents and charters, though some poetry, historiographies, and religious documents are attested as well.
Old Frisian was closely related to and shared common characteristics with the forms of English and Low German spoken during the period. Although earlier scholarship contended that Frisian and English had a closer phylogenetic relationship to each other than Low German, this is no longer the prevailing view. Old Frisian evolved into Middle Frisian around the turn of the 17th century, being largely pushed out by the emergence of Middle Low German as the language of trade in the North Sea. Scholars have argued that the term "Old Frisian" is somewhat misleading, since Old Frisian was contemporary with other Germanic languages during their "Middle" period, such as Middle English and Middle High German.
Grammatically, Old Frisian generally marked for four cases, three grammatical genders, and two tenses, though more complex syntactic functions could be expressed through periphrastic constructions. Its vocabulary comprised a variety of origins including loanwords from Celtic and Slavic languages. Following the Christianization of the Frisians, Latin loans and calques became increasingly common. Word order in Old Frisian was varied; although its typical constituent word order was subject–object–verb, many different word orders are attested in the surviving corpora.

## Classification

Old Frisian was a West Germanic language, which is a part of the larger Germanic language family. It is classified as an Ingvaeonic language along with Old English and Old Saxon. Old Frisian had several distinct regional forms, each leading to later dialects, which were related. According to Rolf Bremmer, the linguistic phylogeny can be described thus:

### Periodization

The periods of the Frisian languages are traditionally divided into Pre–Old Frisian (before 1275), Old Frisian (1275–1550), Middle Frisian (1550–1800), and modern Frisian (1800–present), though these dates have varied among scholars. Larry Trask for example puts the end of the Old Frisian period around 1600, while Han Nijdam [Wikidata] suggests it ends about a hundred years earlier. Some scholars such as Germen de Haan have argued that there is no reason to demarcate them this way and that these periods are more in line with literary periods than linguistic change. Despite its name, Old Frisian was contemporary with Middle Dutch, Middle English, and both Middle High and Middle Low German, though there is some overlap with Old Norse.
According to de Haan, what is referred to as "Old Frisian" should really be called "Middle Frisian" and what is called "Middle Frisian" should be referred to as "Early Modern Frisian". De Haan argues that the current nomenclature is misleading and confusing because it incorrectly suggests that Old Frisian is contemporary other "Old" languages such as Old English and Old Saxon. Alistair Campbell expressed similar views, arguing that the Frisian spoken between the 14th and 16th centuries are better described as "Middle Frisian". In some contexts, the term "Old Frisian" may also refer to what is called either "Pre–Old Frisian" or "Proto-Frisian", or both the Pre–Old Frisian and Old Frisian periods collectively. Frederik Hartmann, for example, cites Bremmer's analysis of Pre–Old Frisian sound changes but refers to the language as "Old Frisian". Bremmer argues that the origins of the "Old" terminology are based in clout for this period, stating that the view of those attempting to give it the "Old" appellation hope "its antiquity will add to its prestige" while acknowledging that the argument is functionally "arbitrary". Ultimately, Bremmer sides with the application of "Middle" to this period except for the two Rüstring codices based on vowel quality in unstressed syllables, itself based on agreed-upon criteria going back to the work of Jacob Grimm.

### Relationship with English

Traditionally, English and the Frisian languages were widely regarded as closer to each other than any other Germanic language. Theodor Siebs is commonly associated with popularizing this affinity and is credited with coining the term "Anglo-Frisian languages" in his 1889 dissertation entitled Zur Geschichte der Englisch-friesischen Sprache ('On the History of the Anglo-Frisian Languages'), though linguists like Henry Sweet articulated the concept as early as 1876. Observations about the close relationship are much older than the 19th century, however; it is likely that the Anglo-Saxon Christian missionaries during the 7th and 8th centuries saw the two languages as closely related. Estimations of a common ancestor of the Anglo-Frisian languages surmise that it was probably fully formed by the 4th or 5th century and began diverging shortly thereafter.
This phylogenetic view of English and Frisian is no longer as widely accepted as it once was, however. Linguists, such as Arjen Versloot [fy] and Patrick Stiles, have argued that while English, Frisian, and Low German are correctly believed to have a common Ingvaeonic ancestor, there is no reason to believe that English and Frisian shared a uniquely close genetic relationship thereafter. Some shared linguistic changes do overlap in ways unique to these languages, often at similar times, but these changes do not match in terms of their relative chronology; that is, these common changes do not appear to have occurred at the same time. Instead, some linguists argue that the Ingvaeonic precursor was likely a broad dialect continuum which saw the dialects which later became English and Frisian develop similarly but not as one language. This continuum was spoken across the continental coast of the North Sea prior to the Migration Period, evolving into distinct languages around turn of the 5th century. The continuum model is sometimes broadened to include the Old Low Franconian as well. Under this model, the two language groups did experience a series of changes particular to the area along the North Sea between about 450 and 650, which influenced both languages as well as Dutch, Flemish, and probably northern varieties of Low German.
The English and the Frisians were long associated with each other. Frisians are traditionally believed to have comprised a fairly significant portion of the Germanic invasions of Britain during the Anglo-Saxon period and, while no major district of England is named after the Frisians, there is toponymic data to support a significant Frisian settlement, including Friston and Frisby. Genetic evidence has suggested that following the Roman-era exodus of the Frisii, the people who later inhabited the area were genetically indistinguishable from the 5th-century Angles who colonized what is now England. Frisian and English domination of maritime trade in the North Sea also played a role in their relationship; London was a hub for Frisian slave-traders and York had a special quarter for housing Frisian merchants. The Anglo-Saxons invaded and subjugated the Frisians during the 5th century, though this is not considered to be a cause for the linguistic similarities.
Other scholars, however, have persisted in supporting the Anglo-Frisian language family as a legitimate phylogenetic category, split into two general outlooks on the relationship. The first is the traditional model, which contends that the relationship is that the two languages diverged from a common Proto-Anglo-Frisian ancestor and thus are sister languages. The other theory is called the convergence hypothesis, which regards Ingvaeonic as the last common ancestor, but holds that early forms of English and Frisian became increasingly intertwined and influenced by each other to form the striking resemblance each shares to the other. This approach to the relationship is credited to Hans Kuhn, who published work on the topic in 1955. Stiles and Hans F. Nielsen both dismissed the convergence approach as unrealistic, pointing to the difficulty of dispersing those kinds of linguistic developments across the maritime divide.

### Dialects

Old Frisian was composed of several dialects. The main division was between Old West Frisian and Old East Frisian, based on their respective position in relation to the Lauwers river; this division predated the Old Frisian period as there is evidence that it was divided on this basis as early as the 8th century. This division was not solely linguistic; the divide was also jurisdictional and ecclesiastical. The diocesean divisions are nearly identical to the dialectal divisions. Old West Frisian, largely coterminous with the Diocese of Utrecht, was divided into two dialects – the southwestern dialect in and around Westergoa and the northeastern dialect in and around Eastergoa – which formed a growing dialect continuum after the sea arm which divided them began to be reclaimed starting in around 1100. Old East Frisian was divided twice as well: Old Weser Frisian in the Diocese of Bremen and Old Ems Frisian [nl; fy] in the Diocese of Münster. During the period of Old Frisian, the dialect which later became North Frisian is not attested. Stiles has argued that both varieties of North Frisian, Insular and Mainland, are ultimately descended from an Eastern Frisian ancestor.
The descendants of Old Weser Frisian are Wangerooge, Wursten, and Harlingerland Frisian, all of which are now extinct. Old Weser Frisian is attested in two full manuscripts and two fragments. Whether the Old Weser Frisian attested in these documents is the direct ancestor of the Wangerooge or Wursten variants or rather an extremely close relative is the matter of some debate; Stiles argues that the document's language is closely related to the two but distinct from them, while Bremmer categorizes them as direct descendants. Old Ems Frisian is the ancestor of the now-extinct Emsingo, Brokmerland, and Ommelanden dialects, as well as the still-extant Saterland Frisian, its only living descendant. Old West Frisian later developed into the modern West Frisian language. In general, Old West Frisian manuscripts, dated to around 1450 to 1525, are more recent attestations compared to Old East Frisian ones, dated to between 1300 and 1450.

## History
### Speakers

The earliest references to the Frisians are found in the works of Roman and Greek authors like Tacitus, as in his Germania, and Ptolemy, described as living from north of the estuary of the Rhine to around the Ems river. Although they were not a part of the Roman Empire, the areas comprising Frisia were akin to a tributary state and some Frisians served as mercenaries in the Roman army. It is uncertain whether the Frisians described by the Romans were Germanic-speaking peoples; onomastic data suggests they spoke an Indo-European language that was neither Germanic nor Celtic, though Old Frisian was a member of the Germanic language family. Following the retreat of Romans from the Low Countries in the 5th century, the Frisians spread considerably over the following two hundred years, dominating the North Sea region. This period is marked by the rule of warlord-like kings and a maritime economy augmented by considerable cattle-breeding skill; Frisian domination of the North Sea during this era led some contemporary non-Frisian documents to refer to the North Sea as the Frisian Sea (Latin: Mare Frisicum). By the early 7th century, the Frisians expanded from the Sincfal [nl] near modern-day Bruges to the Weser estuary. During the latter half of the century, the first wave of Frisians began colonizing the islands off the southwestern coast of modern-day Denmark, occupying the uninhabited islands of Amrum, Föhr, Sylt, and Heligoland; the linguistic descendants of this migration are the Insular North Frisian speakers, who speak Öömrang, Fering, Söl'ring, and Heligoland Frisian varieties, respectively. By the end of the century, they also controlled the coastal regions from the Scheldt to the Rhine. During the following period, Christianity was introduced to the region by Willibrord and Frisia was subjugated by Charles Martel and then later dominated by Charlemagne.
Frisians who spoke Old Frisian during the latter part of the 13th century were divided by the Lauwers river. Those to the west of it were partially conquered by the County of Holland during its long-standing campaigns of conquest, but they were ultimately able to repel Holland's forces, killing its count at the Battle of Warns in 1345. The political situation east of the river is largely obscure during this period, but it appears that they were under regular assault from Saxon forces though were able to keep them at bay. This period is also marked by a loose confederation between the Frisian territories, the Upstalsboom League, which united the Seven Sealands of Frisia and produced legal documents from around 1300, though translations of its original Latin texts only appear in West Old Frisian. The following centuries were marked by civil wars including the Guelders Wars, which saw more Frisian casualties than any war afterward.

### Corpus

Outside the fewer than twenty surviving Pre–Old Frisian runic inscriptions, all of which are dated to between the 6th and 9th centuries and some individual words captured in the marginalia of Latin texts, the earliest Frisian-language text to survive to the modern period is an interlinear gloss of a Latin psalter thought to be from Fivelgo in the modern-day Netherlands and dated to around 1200. The first full manuscripts are the First Brokmer Codex, dated to sometime between 1276 and 1300, and the First Rüstring Codex, dated to around 1300. These documents are known to be copies, but the originals are not known to have survived.
Legal texts dominate the surviving corpus of Old Frisian documents; all but one of the Frisian-language documents east of the Lauwers are legal documents. To the west, however, textual diversity is somewhat wider. Western documents include over a thousand charters and administrative documents, though poetry and historiographies have survived alongside them as well as several religious works. During Latin's descent as the chosen language of legal texts like charters, Frisian began a linguistic decline as Low German was either of higher prestige or was more widely understood. However, Old Frisian documents were still widely translated into Low German from the late 15th century until the turn of the 17th century and modern Low German demonstrates traces of Old Frisian influence, including in placenames, personal names, vocabulary, and syntax. Between the Lauwers and the Ems, no original Frisian texts occur in the record after around 1450 and the last known public document composed in Old Frisian dates to 1547 following the introduction of Dutch as the language of administration by the representatives of Duchy of Saxony.

## Phonology

Old Frisian phonology has been reconstructed using the existing corpora and by analyzing its modern descendants. Orthographically, no distinction was made in early Old Frisian to provide for vowel length, though in later forms of the language an e or i was placed after the vowel to indicate a long vowel, as in baem ('tree'). Geminate consonants, however, were consistently written with duplicated consonants unless they were found in word-final position. The general characteristics of Old Frisian phonology are as follows:
Old Frisian vowels :
| Type | Front | Front | Back | Back |
| Type | short | long | short | long |
| Close | i | iː | u | uː |
| Mid | e | eː, ɛː | o | o:, ɔː |
| Open | | | a | aː |
Old Frisian phonology was not uniform. For example, around the year 1200, the West Germanic phoneme *þ became d in word-medial and word-final positions in several Old Frisian dialects. This change did not affect Weser East Frisian or North Frisian and forms like lathia existed beside ladia in different dialects during the same period. Orthographic conventions used in Old West Frisian help to make the phonological structure much clearer than the Old East Frisian dialects do. Vowel length is frequently marked, either with the addition of an e after the long vowel, as in boek ('book'), or the duplication of the long vowel, as in huus ('house') or wiif ('woman'). Orthographic duplication of long u was sometimes uu and sometimes w, as in hws. Similarly, a long i may sometimes be represented as ij, as in sijn ('his'), or y, as in lyf ('wergeld'). In some instances, y or i may be used as a length modifier as well, as in teyken ('sign') or kuith ('known, public'). The digraph gh is used to represent, the fricative allophone of g. The phoneme /t/ is sometimes written as th though no pronunciation change is thought to have occurred. Similarly, the /sk/ cluster is sometimes written as sch, but it was still likely pronounced as.

### Old Weser Frisian

Short vowels in unstressed final syllables in Old Weser Frisian were in complementary distribution; this distribution is called "vowel balance". When the preceding vowel is short and the introduction of vowel balance would cause the additional short vowel to be in an open syllable, i or u appear, such as in Godi ('to God') or skipu ('ships'). If the preceding vowel was long or a diphthong, or if the stem vowel was separated by another syllable, the word ended with the vowels e or o, such as in liōde ('people'). This regular distribution of word-final vowels has allowed linguists to differentiate between long and short vowels in Old Frisian documents where vowel length is not marked. The consequences of vowel balance is reflected in two of the descendant dialects, Wangerooge and Wursten. Old Weser Frisian also raised e to i before r (irthe 'earth') and raised a and u to i through i-mutation (kining 'king'). However, i was lowered to e and u to o in open syllables if the following syllable contains a. This last process is known as the Rüstring a-mutation. Following fronting and the palatalization of *-ag- and *-eg, which typically became ei, Old Weser Frisian exhibits ī, such as in dī ('day') instead of dei and brīn ('brain') instead of brein. Germanic *ē₂ also became ī.

### Old Ems Frisian

The ancestor of modern Saterland Frisian, Old Ems Frisian diphthongized ē to ei before a voiced alveolar consonant including resonants, as in breid ('bride', also 'broad'). In unstressed syllables, the suffix -en inserted r between the vowel and the final consonant, such as in wēpern ('weapon') instead of wēpen. In later forms of the dialect, a became lengthened after some consonant clusters; ā then had a tendency to become rounded to ō irrespective of if it had been lengthened by the consonant cluster lengthening. This gave rise to forms such as ōlle ('all') instead of alle, though forms like ōlsa ('so') – against the non-Ems form alsā – show rounding but not in both circumstances.

### Old West Frisian

Old West Frisian exhibits rounding of *a before nasal consonants; this was later constrained to the northeastern dialect before -mn or -nn, as the southwestern dialect restored it to a. When v occurred between vowels, it became w, as in howe instead of hove for 'court [dative singular]'; this also sometimes led to the collapse of the two vowel structure, causing a diphthong to occur, as in hāud ('head'; from earlier hāwed inherited from hāved). This sound change is found in later forms of the Old East Frisian dialects. Old West Frisian also exhibits a process called "Jorwert breaking" where long front vowels followed by w are converted into rising diphthongs. This means that,, and were converted into,, and, respectively. Sometimes the j is deleted if it follows an r. Before consonant clusters beginning with a liquid consonant, e is typically raised to i. In consonant clusters where l preceded d, k, n, or r, the preceding e was lengthened, diphthongized, and stress shifted to the second syllable. This process, called "late Old West Frisian breaking", can be seen in examples such as feld lengthening to fēld before breaking into fiēld; stress originally fell on the first syllable, then shifted to the final syllable. Before the cluster nd, e diphthongizes to ei. In the sequence -we-, both elements merge into -o-. The diphthong iā raised to iē, pronounced as. The voiceless dental fricative th became t word-initially and the voiced dental fricative, also represented as th became d word-initially and -medially. Between vowels, d – including those previously dental fricatives – are elided, as in snīa ('to cut'; from earlier snītha). Word-final d was devoiced and u was raised to o before nasal consonants.

## Morphology

Old Frisian distinguished between three grammatical genders: masculine, feminine, and neuter. Case appears to have been somewhat variable; while nominative, accusative, genitive, and dative cases are abundant, the instrumental case was preserved in some fossilized phrases and a locative case has been documented in a few attestations. The only two attested numbers are found in Old Frisian (singular and plural), though a dual number is attested in both Insular and Mainland forms of North Frisian, becoming obsolete during the early 20th century. Old Frisian likely had a dual number, but the legal context in which most attestations occur did not give cause for the use of the dual. Old Frisian did not have reflexive pronouns for most of its history; although the inherited reflexive sīn is attested, it displaced the expected neuter genitive singular pronoun *his and the language instead used the accusative case to express the reflexive grammatical function.

### Pronouns

Pronouns in Old Frisian were only attested in four cases: nominative, accusative, genitive, and dative. Like other Invaeonic languages such as Old English and Old Saxon, there is no distinction between the accusative and dative, which is contrasted with other West Germanic languages like Old High German.
First- and second-person pronouns :
| | First person | First person | Second person | Second person |
| | Singular | Plural | Singular | Plural |
| Nominative | ik | wī | thū | jī, ī, gī |
| Accusative | mī | ūs | thī | iu, io |
| Genitive | mīn | ūser | thīn | iuwer |
| Dative | mī | ūs | thī | iu, io |
Old West Frisian innovated the second-person plural form iemman, sometimes rendered as iemma, a univerbation of jī and man (literally 'you men'). This form did not decline for case and jī remained the polite form of address. Old Frisian had cliticized pronouns which were attached to the end of words; their use has made translation more difficult since they are not marked as distinct from other homonymic suffixes. Possessive pronouns declined like strong adjectives and interrogative pronouns did not decline for grammatical gender. The interrogative pronoun hwet ('what') is sometimes marked for number, but only in the accusative and dative forms. The interrogative pronoun hwa ('who') was typically pronounced with a short vowel, but pronounced long utterance-finally.
Pronominal forms were sometimes used to recapitulate nouns and other pronouns in order to establish clarity. Examples include:
Thi
that
blata
poor man
thi
that
is
is
lethost
most miserable
allera
all-GEN-PL
nata.
companion-GEN-PL
Thi blata thi is lethost allera nata.
that {poor man} that is {most miserable} all-GEN-PL companion-GEN-PL
'The poor man, he is the most miserable of all companions.'

### Nouns

Old Frisian nouns are classified into three archetypes. Type I are weak/consonant-stemmed nouns, type II are strong/vowel-stemmed nouns, and type III is a catch-all category which mainly comprises other kinds of consonant-stemmed nouns of which the Indo-European reflex had the case marked immediately to the root word. Masculine words ending in -a and feminine or neuter words ending in -e are classed in type I, though there are only two neuter words in this type: āre ('ear') and āge ('eye'). Type II comprises a wide variety of strong masculine nouns and predominately abstract feminine nouns. The neuter suffix -skipi or -skipe also governs the type II paradigm, though this attested as a feminine suffix as well. Below is an example of an n-stem declension, a kind of type I declension pattern:
n-stem declension :
| | Masculine | Masculine | Feminine | Feminine | Neuter | Neuter |
| | skelta 'bailiff' | skelta 'bailiff' | tunge 'tongue' | tunge 'tongue' | āge 'eye' | āge 'eye' |
| | Singular | Plural | Singular | Plural | Singular | Plural |
| Nominative | skelta | skelta | tunge | tunga | āge | āgne |
| Accusative | skelta | skelta | tunga | tunga | āge | āgne |
| Genitive | skelta | skeltena | tunga | tungena | āga | āgena |
| Dative | skelta | skeltum | tunga | tungum | āga | āgum |
Heavy syllables in the stem – that is, stems with either a long vowel or a word-final consonant cluster – have an influence on the pattern of type II declensions. Traditionally ending in -u, heavy a-stems lose the pluralizing suffix, making the nominative and accusative forms of the plural identical to the singular. Below are examples of a-stem declensions within the type II paradigm:
a-stem declension :
| | Masculine | Masculine | Neuter | Neuter | Neuter (heavy) | Neuter (heavy) |
| | bām 'tree' | bām 'tree' | skip 'boat' | skip 'boat' | word 'word' | word 'word' |
| | Singular | Plural | Singular | Plural | Singular | Plural |
| Nominative | bām | bāmar | skip | skipe | word | word |
| Accusative | bām | bāmar | skip | skipe | word | word |
| Genitive | bāmes | bāma | skipes | skipa | wordes | worda |
| Dative | bāme | bāmum | skipe | skipum | worde | wordum |
Certain words have irregular plurals due to phonological processes, such as dei ('day') and degar ('days') which developed based on vowel fronting and velar palatalization in the former but not in the latter. These irregularities do not affect its paradigm classification.
All nouns in the ō-stem declension were feminine. The nominative singular -e in these terms comes from an originally accusative form. Below is an example of the ō-stem paradigm:
ō-stem declension :
| | Feminine | Feminine | Feminine | Feminine |
| | ieve 'gift' | ieve 'gift' | wunde 'wound' | wunde 'wound' |
| | Singular | Plural | Singular | Plural |
| Nominative | ieve | ieva | wunde | wunda |
| Accusative | ieve | ieva | wunde | wunda |
| Genitive | ieve | ieva | wunde | wunda |
| Dative | ieve | ievum | wunde | wundum |

### Verbs

Verbs in Old Frisian comprised four types: strong, weak, preterite-present, and anomalous. In general and with few exceptions, the only productive verb declension was the weak paradigm. Some paradigm leveling to weak declensions occurred among strong verbs in later forms of the language. The anomalous class of verbs are a composite class comprising suppletive verbs, verbs without clear preterite forms, and verbs with defective or missing declension forms. In general, verbs tended to end in either -a or -ia with later forms reduced to -a or -ia, respectively. Noteworthy exceptions include gān and stān in Old West Frisian; this word-final -n became more widespread in monosyllabic verbs in later forms of that dialect, such as in dwān ('to do') and siān ('to see'). Infinitive forms used the lengthened suffix -ane after the word tō – used to express purpose – such as in the phrase tō farane ('to travel'). In Old Weser Frisian and Old Ems Frisian, present participles and gerunds had identical forms. Like modern English, the conjunction thet ('that') was sometimes omitted after verbs of expression in some contexts (Tha spreken se hia ne kuden. 'Then they said [that] they were unable to.').

#### Strong verbs

The infinitive, the first- and third-person singular preterite, the plural preterite, and the past participle are the four constituent parts identifying a strong verb based on the vowel gradation, including changes to vowel quality or length, that signals a change in meaning. Like nominal declensions, phonological explanations for irregularity are present and similarly do not change classification. There were six classes of strong verbs in Old Frisian with a seventh catch-all category. Classes IV and V became functionally identical after a morphophonological change and are distinguished only by historical provenance. Examples of verbal paradigms can be seen below:
Verb classes :
| | Infinitive | Third-person singular present | Preterite | Preterite | Past participle |
| | Infinitive | Third-person singular present | Singular | Plural | Past participle |
| Class I | grīpa | gripth | grēp | gripen | gripen |
| 'to seize' | grīpa | gripth | grēp | gripen | gripen |
| Class II | biāda | biuth | bād | beden | beden |
| 'to offer' | biāda | biuth | bād | beden | beden |
| Class III | helpa | helpth | halp | hulpen | hulpen |
| 'to help' | helpa | helpth | halp | hulpen | hulpen |
| Class IV | bifela | bifelth | bifel | bifēlen | bifelen |
| 'to order' | bifela | bifelth | bifel | bifēlen | bifelen |
| Class V | lesa | lesth | les | lēsen | lessen |
| 'to read' | lesa | lesth | les | lēsen | lessen |
| Class VI | fara | ferth | fōr | fōren | faren |
| 'to go' | fara | ferth | fōr | fōren | faren |
| Class VII | slēpa | slept | slēp | slēp | slēpen |
| 'to sleep' | slēpa | slept | slēp | slēp | slēpen |

#### Weak verbs

Unique to Old Frisian, there were only two weak verb classes; Gothic had twice as many, while Old Norse, Old English, Old Saxon, and Old High German each had three. Class I weak verbs comprised verbs which originally had a suffix, *-jan, which created causative verbs from strong verb stems and factitive verbs from nouns and adjectives, such as dēma ('to judge') from dōm ('judgement'). Morphophonologically, the *j affected consonants through assibilation and the vowels through mutation. Class I weak verbs have the past tense suffix -de, or -te after voiceless consonants. Geminated consonants become simple in the preterite and past participles. By contrast, class II weak verbs are typically those which end in -ia. These verbs have their past tense marked by the deletion of the i and the addition of the suffix -ade; the past participle is formed with the same deletion and a simple -ad suffix. Later forms of the suffixes are -ede and -ed, respectively. In late Old West Frisian, these past tense suffixes were deleted. Class II has remained productive into the modern period; Frisian is the only branch of West Germanic languages to have maintained this class of verbs.

#### Preterite-present

Germanic languages have a verb class in which a form resembling a past-tense strong verb supplies the present-tense meaning while the past-tense form is re-formed with a weak verbal suffix; infinitive forms are also formed through innovation. These verbs exhibit expected vowel alternations for strong verbs for some forms while other forms are in line with expected weak verb declensions. These verbs are categorized into one of the six strong verb classes the strong verb form is derived from.

## Vocabulary

Although the vast majority of Old Frisian vocabulary can be traced directly from Proto-Germanic, many terms were created through compounding or affixation, and borrowed from other languages. With limited exceptions, stress fell on the stem in Old Frisian. Only a few adverb-forming suffixes are attested; adverbs could be otherwise be formed using either the genitive or dative cases. Nouns were regularly combined without any use of genitive forms, such as in fiskdam ('fishing weir'), though it became increasingly common to mark the first element with a linking genitive form like -s, such as in sumeresnacht 'summer night'. Adjectives were also compounded with nouns to form other adjectives, such as ūdertam ('easy to milk', lit. 'udder-tame'). Although relatively rare, kennings are attested in Old Frisian documents. For example, criminal regulations regarding the protection of children and pregnant women use the term bēnenaburch ('fortress of the bones') to reference the womb.
Loanwords in Old Frisian comprised inherited borrowings from earlier languages – such as rīke ('kingdom, realm') borrowed from a Celtic language during either the Proto-Germanic or Proto–West Germanic periods – and borrowings during the Old Frisian period. Old Frisian borrowed a number of Latin terms from both periods and it is often difficult to pinpoint precisely when the Latin loan entered the language. After the Christianization of the Frisians, the language experienced an influx of Latin and Greek loans, such as diōvel ('devil'; from Latin diabolus), skrīva ('to write'; from Latin scrībere, displacing the native term wrīta), and seininge ('blessing'; from Latin signum 'sign of the cross'). Since the Anglo-Saxons were the ones who converted the Frisians, it is probable that Old English terms began to enter the language around this time, though the close relationship between the two languages makes distinguishing native words from Old English borrowings extremely difficult. Possible borrowings may include trachtia ('to yearn'; from Old English treahtian 'to comment on') and diligia ('to delete'; from Old English dīlegian 'to blot out, to erase'), though these terms may have been borrowed from Old English to missionary centers in German-speaking areas and then into Old Frisian. Similarly, Old and Middle Low German served as an intermediary for Old and Middle High German borrowings; these include terms like keisere ('emperor'; from Old High German kaisar) and iunkfrouwe ('young woman, virgin').
Old and Middle Low German contributed significantly to loanwords and began to dominate the language of trade in the North Sea by the end of the 15th century, displacing Old Frisian dialects spoken east of the Lauwers. Terms borrowed include reth ('wheel'; from Old Low German rath) and swāger ('brother-in-law'). Old Frisian also appears to have borrowed terms from the Slavic languages through Low German, including the term cona ('fur') which was used as money in Rüstringen (compare the Serbo-Croatian term kuna). Terms from Old French were also borrowed, probably through one or more intermediaries. Examples include payement ('payment') and amīe ('female lover, concubine'). Old Frisian also borrowed a number of abstract suffixes from French.
Calques were common in Old Frisian, especially for Latin terms adopted during the Christianization of the Frisians, such as godeshūs ('church', lit. 'God's house'; Latin domus Dei) and elemechtich ('almighty'; Latin omnipotens). Other loan translations include the days of the week and some terms associated with the military or leadership roles, such as hāvedmon ('leader, chieftain'; Latin capitaneus) and herestrēte ('highroad, military road'; Latin via militaris).

## Syntax
### Case

Case did not vary in Old Frisian by much when compared to other contemporary Germanic languages. The nominative case was used for the subjects or subject complements though it was also used in vocative contexts. While the main use of the accusative was to mark the direct object of a verb, Old Frisian was also used in temporal and spatial expressions, such as mentioning spaces of time (niugen monath 'nine months') or distances (Hi gunge tha niugen heta skera. 'He should walk the nine hot plowshares.'). Genitive usage was complex and multifaceted; it marked possession and relationships, but was also used to mark adverbs and had both partitive and numerical functions including measures (tha wi sigun hundred folkes santon 'when we sent seven hundred [armed] men') and counting (thritich fethma 'thirty fathoms').
The dative case was also complex. Although it marked the indirect object of a ditransitive verb, it was sometimes used for the direct objects of transitive verbs, such as helpa ('to help'). The dative shared some overlap in function with the genitive, including its use in adverbial phrases and measurements. Dative constructions are also used to mark the benefactive, such as in the sentence God him reste ('God rested [for himself]'). A number of adjectives govern the dative as well, typically marking either physical or emotional closeness.
As the case system began to break down in Old Frisian, authors – especially those of legal documents – came to rely heavily on word order and changed the use of prepositions. By late Old Frisian, case marking was optional.

### Verbs

Old Frisian marked for two tenses in the verbal root: simple present and simple past, also called the simple preterite. All other tenses, called compound tenses, were expressed through periphrasis using auxiliary verbs. While these tenses were not common in earlier forms of the language, they became more popular over time. Compound tenses used the auxiliaries meaning 'to have' (hebba in Old East Frisian, habba in Old West Frisian) and 'to be' (wesa). The use of hebba/habba and the past participle were used to express the past perfective and less commonly the pluperfect. These usages were largely constrained to dependent clauses. The use of wesa is less clear, but it appears to have been used as somewhat of a present progressive when in combination with a present participle. It is often difficult to differentiate between a progressive semantic meaning or a copular relationship. Particularly with verbs of motion, wesa was also used in some intransitive contexts to express the perfect or pluperfect to express changes in state. The perfect of wesa was used with hebba/habba, though this was uncommon in earlier forms of the language. The passive voice was typically constructed with the verb wertha ('to become') and the past participle, though wesa and the past participle could be used to form a perfective passive. The combined use of wesa and the present participle were used for the durative aspect, while the future tense used the combination of the auxiliary skela and the infinitive. Non-auxiliary verbs, such as biginna ('to begin') and gunga ('to go'), were used with the infinitive to express an inchoative aspect. Similarly, verbs like dwā ('to do') and lēta ('to let') were used to form the causative.
The language also marked for three moods in the root: indicative for statements of fact or observations, subjunctive for subjective thoughts including guesswork and conjecture, and imperative for commands. The indicative and subjunctive moods may be used next to each other in different clauses of the same sentence. The infinitive was used in several ways, but the inflected infinitive – an infinitive preceded by tō – operated as a gerund. This inflected form was used to express purpose and sentences containing it would often drop the subject and the associated finite verb. A unique construction using the uninflected infinitive, called the accusative-plus-infinitive construction, was sometimes used as a complement, as in tha segen hia anne thretundista sitta ('then they saw sitting a thirteenth [man]').

### Word order

Word order in Old Frisian varied widely depending on context and function. The language's constituent word order is generally described as subject–object–verb. Dependent clauses strongly tend towards this word order as well, though some departures from this trend are attested. However, analysis of the existing corpora involving charter documents shows that dependent sentences with direct objects show about 60% have a subject–verb–object construction. Object–verb–subject constructions were commonly employed as a method of topicalization and both conditional and interrogative clauses were typically verb–subject–object. Dependent conditional clauses use object–subject–verb constructions as well when interrogative pronouns are in grammatical cases other than the nominative.
In oblique contexts, pronouns may be moved to between the verb and the subject when the subject in a later position than the verb, leading to a verb–object–subject word order. This word order is completely absent in modern Frisian. Examples of this include the following:
tha
then
het
called
se
them
thi
the
koning
king
alle
all
heran
lords
tha het se thi koning alle heran
then called them the king all lords
'then the king called them all lords'
Like all other Germanic languages at some point in their history, Old Frisian exhibits properties of verb-second word order, though its application is inconsistent. This means that the verb appears in the second position in independent clauses with a finite verb, but reverts to verb-final word order in subordinate clauses.
Old Frisian sentences almost always required a subject and the language often employed the use of dummy subjects. This appears to be a syntactic necessity even when there was not semantic function. Examples include verbs involving the weather and impersonal passives, respectively demonstrated below:
hwant
for
hit
it
wayt
blows
ende
and
stormit
storms
alle
all
daghen
days
hwant hit wayt ende stormit alle daghen
for it blows and storms all days
'for it blows and storms all days'
hwersar
when there
fuchten
fought
is
is
in
in
tha
the
godes
god-GEN
huse
house
hwersar fuchten is in tha godes huse
{when there} fought is in the god-GEN house
'when there has been fought in the house of God'

### Negation

In Old Frisian, negative sentences could be derived from the simple addition of a negative element, such as naet ('not') or nimmen ('nobody'), or double negative constructions. While there is a preference in the language for double negatives, all three stages of Jespersen's cycle are present in the existing corpora, though neither of the two Rüstringer codices – the two oldest codices – exhibit the last stage. The negative marker ne precedes the finite verb in both kinds of constructions. Examples include:
truch
through
thet
that
hia
they
ne
NEG
mughen
may
cuma
come
truch thet hia ne mughen cuma
through that they NEG may come
'through that, they may not come'
thet
that
hi
he
ter
there
nauuet
not
cuma
come
ne
NEG
machte
might
thet hi ter nauuet cuma ne machte
that he there not come NEG might
'that he might not come there'
The negative marker ne often cliticized to the following auxiliary, such as in nabba ('to not have'; from ne + habba) and nis ('is not'; from ne + is). In sentences where the finite verb is elided, the negative marker is also elided and no words nor any affixes can come between them. For these reasons, the negative marker and the verb are seen as a unified syntactic unit, with ne serving the function of a syntactic clitic. This is not the case for other negative elements, such as naet, which can be divided by other syntactic functions. Contrastive examples of this are demonstrated below, both from the Skeltana Riucht:
dat
that
hi
he
dine
the
kempa
champion
winna
defeat
ne
NEG
mey
may
dat hi dine kempa winna ne mey
that he the champion defeat NEG may
'that he may not defeat the champion'
ief
if
hi
he
dine
the
kempa
champion
naet
not
winna
defeat
mey
may
ief hi dine kempa naet winna mey
if he the champion not defeat may
'if he may not defeat the champion'
In sentences where the only verb is a finite verb in a main clause, the use of naet is mostly restricted to the sentence-final position, but in subordinate clauses with double negatives, naet is promoted to before ne.