# -eo
## Italian
### Etymology 1

Borrowed from Latin -eus.

#### Pronunciation

* IPA: /e.o/ (stress falls on the preceding syllable)
* Hyphenation: -e‧o

#### Suffix

-eo (adjective-forming suffix, feminine -ea, masculine plural -ei, feminine plural -ee)
* used to form adjectives referring to the qualities of the root noun; -en, -eous, -ean
** used to form adjectives from materials or substances, indicating material composition:
    ‎ferro (“iron”) + ‎-eo → ‎ferreo (“made of iron”)
    ‎argento (“silver”) + ‎-eo → ‎argenteo (“made of silver”)
    ‎acqua (“water”) + ‎-eo → ‎acqueo (“made of water, watery”)
** used to form relational adjectives from proper nouns:
    ‎Cesare (“Caesar”) + ‎-eo → ‎cesareo (“Caesarean, of or pertaining to Julius Caesar”)
    ‎Medici + ‎-eo → ‎mediceo (“of or pertaining to the Medici family”)

##### Usage notes

* Some adjectives in -eo are borrowed directly from Latin and exhibit fossilized characteristics which are otherwise lost in the root noun:
** corpo (“body”) → corporeo (“bodily, corporeal”) (cfr. Latin corpor-, oblique stem of corpus)
** legno (“wood”) → ligneo (“wooden, made from wood”) (cfr. Latin lignum)
** oro (“gold”) → aureo (“golden, made of gold”) (cfr. Latin aurum)
** Ercole (“Hercules”) → erculeo (“Herculean, pertaining to Hercules”) (cfr. Latin Herculēs)

### Etymology 2

Borrowed from Latin -aeus, from Ancient Greek -αῖος (-aîos).

#### Pronunciation

* IPA: /ˈɛ.o/
* Rhymes: -ɛo
* Hyphenation: -è‧o

#### Suffix

-eo (adjective-forming suffix, feminine -ea, masculine plural -ei, feminine plural -ee) -eo m (noun-forming suffix, plural -ei, feminine -ea)
* used to form adjectives and nouns expressing relation to the root noun; -an, -ean
** forming ethnonyms from place names:
    ‎Etna + ‎-eo → ‎etneo (“of or pertaining to mount Etna; person from or inhabitant of the Etna region”)
    ‎Ragusa (city in Croatia) + ‎-eo → ‎raguseo (“of or pertaining to the city of Ragusa; person from or inhabitant of Ragusa”)
** forming relational adjectives from proper nouns:
    ‎Euclide (“Euclid”) + ‎-eo → ‎euclideo (“Euclidean, pertaining to Euclid”)
    ‎Augusto (“Augustus”) + ‎-eo → ‎augusteo (“Augustan, pertaining to emperor Augustus or his time”)
** forming relational adjectives from body parts:
    ‎carotide (“carotid”) + ‎-eo → ‎carotideo (“pertaining to a carotid”)
    ‎faringe (“pharynx”) + ‎-eo → ‎faringeo (“pharyngeal, pertaining to the pharynx”)

### Derived terms
## Latin
### Pronunciation

* (Classical Latin) IPA: /e.oː/, [eoː]
* (modern Italianate Ecclesiastical) IPA: /e.o/, [eo] (stressed on the antepenult)

### Etymology 1

From Proto-Italic *-ēō, from earlier *-ējō, from verbs with Proto-Indo-European *-éh₁yeti (stative suffix) in which the first person singular always ended in *-éh₁yoh₂.

#### Suffix

-eō (present infinitive -ēre); second conjugation, no perfect or supine stems
* Forms stative verbs from adjectives.
    ‎clārus (“clear”) + ‎-eo → ‎clāreō (“to be clear”)
    ‎frīgus (“cold”) + ‎-eo → ‎frīgeō (“to be cold”)

##### Conjugation

$^1$At least one use of the Old Latin "sigmatic future" and "sigmatic aorist" tenses is attested, which are used by Old Latin writers; most notably Plautus and Terence. The sigmatic future is generally ascribed a future or future perfect meaning, while the sigmatic aorist expresses a possible desire ("might want to"). It is also attested as having a rare sigmatic future passive indicative form ("will have been"), which is not attested in the plural for any verb.

##### Derived terms

* -ēscō

### Etymology 2

From Proto-Italic *-eō, from causative/frequentative verbs with Proto-Indo-European *-éyeti (causative suffix) in which the first person singular ended in *-éyoh₂.

#### Suffix

-eō (present infinitive -ēre); second conjugation, no perfect or supine stems
* (no longer productive) Forms causative verbs from primary (third conjugation and some fourth conjugation) verbs.

##### Conjugation

$^1$At least one use of the Old Latin "sigmatic future" and "sigmatic aorist" tenses is attested, which are used by Old Latin writers; most notably Plautus and Terence. The sigmatic future is generally ascribed a future or future perfect meaning, while the sigmatic aorist expresses a possible desire ("might want to"). It is also attested as having a rare sigmatic future passive indicative form ("will have been"), which is not attested in the plural for any verb.

### Etymology 3

See the etymology of the corresponding lemma form.

#### Suffix

-eō
* dative/ablative masculine/neuter singular of -eus

### References

* Sihler, Andrew L. (1995) New Comparative Grammar of Greek and Latin, Oxford, New York: Oxford University Press, →ISBN

## Spanish
### Etymology 1

From Latin -eus.

#### Suffix

-eo (adjective-forming suffix, feminine -ea, masculine plural -eos, feminine plural -eas)
* -eous; forms adjectives meaning resembling or having characteristics of the related term

##### Related terms

* -áceo
* -áneo
* -io

### Etymology 2
#### Suffix

-eo m (noun-forming suffix, plural -eos)
* forms nouns from verbs suffixed with -ear, meaning 'action and effect'

##### Derived terms
### Further reading

* “-eo”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8, Royal Spanish Academy [Spanish: Real Academia Española], 2024 December 10