English irregular verbs
The English language has many irregular verbs, approaching 200 in normal use—and significantly more if prefixed forms are counted. In most cases, the irregularity concerns the past tense (also called "preterite") or the past participle. The other inflected parts of the verb—the third person singular present indicative in "-[e]s", and the present participle and gerund form in "-ing"—are formed regularly in most cases. There are a few exceptions: the verb "be" has irregular forms throughout the present tense; the verbs "have", "do", and "say" have irregular "-[e]s" forms; and certain defective verbs (such as the  modal auxiliaries) lack most inflection. The irregular verbs include many of the most common verbs: the dozen most frequently used English verbs are all irregular. New verbs (including loans from other languages, and nouns employed as verbs) usually follow the regular inflection, unless they are compound formations from an existing irregular verb (such as "housesit", from "sit"). Irregular verbs in Modern English are typically derived from verbs that followed more regular patterns at a previous stage in the history of the language. In particular, many such verbs derive from Germanic strong verbs, which make many of their inflected forms through  vowel gradation, as can be observed in Modern English patterns such as "sing–sang–sung". The regular verbs, on the other hand, with their preterites and past participles ending in "-ed", follow the weak conjugation, which originally involved adding a dental consonant ("-t" or "-d"). Nonetheless, there are also many irregular verbs that follow or partially follow the weak conjugation. For information on the conjugation of regular verbs in English, as well as other points concerning verb usage, see English verbs. Development. Most English irregular verbs are native, derived from verbs that existed in Old English. Nearly all verbs that  have been borrowed into the language at a later stage have defaulted to the regular conjugation. There are a few exceptions, however, such as the verb "catch" (derived from Old Northern French "cachier"), whose irregular forms originated by way of analogy with native verbs such as "teach". Most irregular verbs exist as remnants of historical conjugation systems. When some grammatical rule became changed or disused, some verbs kept to the old pattern. For example, before the Great Vowel Shift, the verb "keep" (then pronounced /keːp/, slightly like "cap" or "cape" without the j-glide) belonged to a group of verbs  whose vowel was shortened in the past tense; this pattern is preserved in the modern past tense "kept" (similarly "crept", "wept", "leapt", "left"). Verbs such as "peep", which have similar form but arose after the Vowel Shift, take the regular "-ed" ending. The force of analogy tends to reduce the number of irregular verbs over time, as irregular verbs switch to regular conjugation patterns (for instance, the verb "chide" once had the irregular past tense "chid", but this has given way to the regular formation "chided"). This is more likely to occur with less common verbs (where the irregular forms  are less familiar); hence it is often the more common verbs (such as "be", "have", "take") that tend to remain irregular. Many irregular verbs today have coexisting irregular and regular forms (as with "spelt" and "spelled", "dreamt" and "dreamed", etc.). In a few cases, however, analogy has operated in the other direction (a verb's irregular forms arose by analogy with existing irregular verbs). This is the case with the example of "catch" given above; others include "wear" and "string", which were originally weak verbs, but came to be conjugated like the similar-sounding strong verbs "bear" and "swing". In  American English, the regular forms of verbs account for more than 90% of instances, whereas British English has a regular form frequency of 69% according to a 1991 study. The verb forms described in this article are chiefly those that are accepted in standard English; many regional dialects have different irregular forms, such as American English "sneak"–"snuck" and "dive"-"dove" as opposed to standard "sneaked" and "dived" respectively. In particular, it is fairly common in some types of non-standard speech to use (standard) past tenses as past participles, and vice versa; e.g. "have went" instead of "have gone" in Southern  American English. Groups. The irregular verbs of Modern English form several groups with similar conjugation pattern and historical origin. These can be broadly grouped into two classes – the Germanic weak and strong groups – although historically some verbs have moved between these groups. There are also a few anomalous cases: the verbs "be" and "go", which demonstrate suppletion; the verb "do"; and the defective modal verbs. Strong verbs. Many irregular verbs derive from Germanic strong verbs, which display the vowel shift called ablaut, and do not add an ending such as "-ed" or "-t" for the past forms. These sometimes retain  past participles with the ending "-[e]n", as in "give–gave–given" and "ride–rode–ridden", but in other cases this ending has been dropped, as in "come–came–come" and "sing–sang–sung". This verb group was inherited from the parent Proto-Germanic language, and before that from the Proto-Indo-European language. It was originally a system of regular verbs, and in Old English and modern German the system remains more or less regular; however in Modern English relatively few verbs continue to follow such a pattern, and they are classed as irregular. Verbs that retain a strong-type  inflection in modern English and add "-[e]n" in the past participle include "bear", "beat", "beget", "bite", "blow", "break", "choose", "cleave", "draw", "drive", "eat", "fall", "fly", "forbid", "forget", "forsake", "freeze", "give", "grow", "know", "lie", "ride", "rise", "see", "shake", "shear", "slay", "smite", "speak", "steal", "stride", "strive", "swear", "take", "tear", "throw", "tread", "wake", "weave", and "write". Those that do not add "-[e]n" in the usual past participle include "become", "begin", "bind", "burst", "cling", "come", "drink", "fight", "find", "fling", "get" (but with past participle "gotten" in Scottish, Irish and American English), "grind", "hang", "hold", "let", "ring", "run", "seek", "shed", "shine", "shit", "shoot", "shrink", "sing , sink", "sit", "slide", "sling", "slink", "slit", "spin", "spring", "stand", "sting", "stink", "strike", "swim", "swing", "win", "wind" and "wring". The verbs "sow" and "swell" are now usually regular in the past tense, but retain the strong-type past participles "sown" and "swollen". Other verbs retain participles in "-n" for certain adjectival uses and distinguish them from other usage in perfect tenses ("He is drunk" vs "drunken sailor", "The shirt has shrunk" vs "shrunken hands" or "The ship was sunk" vs "sunken cheeks"). The participle in "-n" may sometimes be limited to certain specific usage, as in "molten" used only to refer  to metals (compare "molten steel" vs "melted butter"). Sometimes the connection between the infinitive and the adjective (i.e. originally the past participle form) is not perceived as obvious any more, e.g. "seethe – sodden". The verb "crow" is now regular in the past participle, but the strong past tense "crew" is sometimes used. Some originally weak verbs have taken on strong-type forms by analogy with strong verbs. These include "dig", "dive" (when "dove" is used as the past tense), "hide", "prove" (when "proven" is used as the past participle), "saw" (past participle "sawn"), "sew" (past participle "sewn"), "show" (past participle  shown), "spit", "stick", "strew", "string", and "wear" (analogy with "bear"). For indication of the groups of strong verbs the listed words belong to, see the table at List of English irregular verbs. Weak verbs. Some other irregular verbs derive from Germanic weak verbs, forming past tenses and participles with a "-d" or "-t" ending (or from originally strong verbs that have switched to the weak pattern). The weak conjugation is also the origin of the regular verbs in "-ed"; however various historical sound changes (and sometimes spelling changes) have led to certain types of irregularity in some verbs. The main  processes are as follows (some verbs have been subject to more than one of these). The irregular weak verbs (being in normal use) can consequently be grouped as follows: For weak verbs that have adopted strong-type past tense or past participle forms, see the section above on strong verbs. More information on the development of some of the listed verbs can be found at List of irregular verbs. Anomalous cases. The following verbs do not fit exactly into any of the above categories: Verbs with irregular present tenses. Apart from the modal verbs, which are irregular in that they  do not take an "-s" in the third person (see above), the only verbs with irregular present tense forms are "be", "do", "have" and "say" (and prefixed forms of these, such as "undo" and "gainsay", which conjugate in the same way as the basic forms). The verb "be" has multiple irregular forms. In the present indicative it has "am" in the first person singular, "is" in the third person singular, and "are" in the plural and second person singular. (Its present subjunctive is "be", as in "I suggest that you be extremely careful", though that is not irregular, as all  verbs use the infinitive/imperative form for the present subjunctive.) It also has two past tense forms: "was" for the first and third persons singular, and "were" for the plural and second person singular (although there are certain subjunctive uses in which "were" can substitute for "was," as in "If I were you…" or "I wish I were there"). The past participle is "been", and the present participle and gerund forms are regular: "being". For more details see Indo-European copula. As mentioned above, apart from its other irregularities, the verb "do" has the third person present indicative "does" pronounced  with a short vowel: . The verb "have" has a contracted third person present indicative form: "has" (weak pronunciation ). This is formed similarly to the verb's past tense "had". The verb "say" displays vowel shortening in the third person present indicative (although the spelling is regular): "says" . The same shortening occurs in the past form "said" . (Compare the diphthong in the plain form "say" .) For shortened forms of certain verbs and of their negations ("s", "re", "won't", etc.), see English auxiliaries and contractions. Coincident forms. In regular English verbs, the past tense and past participle have the same form . This is also true of most irregular verbs that follow a variation of the weak conjugation, as can be seen in the list below. Differences between the past tense and past participle (as in "sing–sang–sung", "rise–rose–risen") generally appear in the case of verbs that continue the strong conjugation, or in a few cases weak verbs that have acquired strong-type forms by analogy—as with "show" (regular past tense "showed", strong-type past participle "shown"). However, even some strong verbs have identical past tense and participle, as in "cling–clung–clung". In some verbs, the past  tense, past participle, or both are identical in form to the basic (infinitive) form of the verb. This is the case with certain strong verbs, where historical sound changes have led to a leveling of the vowel modifications: for example, "let" has both past tense and past participle identical to the infinitive, while "come" has the past participle identical (but a different past tense, "came"). The same is true of the verbs listed above under as having undergone coalescence of final consonants (and without other irregularities such as vowel shortening or devoicing of the ending): "bet", "bid", etc. (these verbs  have infinitive, past tense and past participle all identical, although some of them also have alternative regular forms in "-ed"). The verb "read" has the same spelling in all three forms, but not the same pronunciation for the past tense and past participle , as it exhibits vowel shortening. In a few cases the past tense of an irregular verb has the same form as the infinitive of a different verb. For example, "bore" and "found" may be past tenses of "bear" and "find", but may also represent independent (regular) verbs of different meaning. Another example is "lay", which may be  the past tense of "lie", but is also an independent verb (regular in pronunciation, but with irregular spelling: "lay–laid–laid"). In fact "lay" derives from a causative of the verb from which "lie" derives. The two verbs are sometimes confused, with "lay" used in the intransitive senses prescriptively reserved for "lie". Prefixed verbs. Nearly all of the basic irregular verbs are single-syllable words. Their irregular inflected forms are generally single-syllable also, except for the past participles in "-en" like "chosen" and "risen". However, many additional irregular verbs are formed by adding prefixes to the basic ones: "understand  from stand", "become" from "come", "mistake" from "take", and so on. As a general rule, prefixed verbs are conjugated identically to the corresponding basic verbs; e.g "understand–understood–understood" and "become–became–become", following the patterns of "stand–stood–stood" and "come–came–come". However, there are occasional differences: in British English, for instance, the past participle of "get" is "got", (as opposed to "gotten" as in North American English) while that of "forget" is "forgotten". Only a few irregular verbs of more than one syllable cannot be analyzed as prefixed compounds of monosyllables. The only ones in normal  use are "begin–began–begun" and "forsake–forsook–forsaken" (these both derive from prefixed verbs whose unprefixed forms have not survived into Modern English). There is also "beseech–besought–besought" (this is from Old English "besēcan" "to seek or inquire about", making it equivalent to "be-" + "seek", but it has moved away from "seek" in both form and meaning); however the form "besought" is now archaic, the verb normally being conjugated regularly ("beseeched"). List. The following is a list of 204 irregular verbs that are commonly used in standard modern English. It omits many rare, dialectal, and archaic forms , as well as most verbs formed by adding prefixes to basic verbs ("unbend", "understand", "mistake", etc.). It also omits past participle forms that remain in use only adjectivally ("clad", "sodden", etc.). For a more complete list, with derivations, see List of English irregular verbs. Further information, including pronunciation, can be found in Wiktionary. The list that follows shows the base, or infinitive form, the past tense and the past participle of the verb. In language acquisition. Steven Pinker's book "Words and Rules" describes how mistakes made by children in learning irregular verbs throw light on the mental processes involved  in language acquisition. The fact that young children often attempt to conjugate irregular verbs according to regular patterns indicates that their processing of the language involves the application of rules to produce new forms, in addition to the simple reproduction of forms that they have already heard. See also .