-o

combibere (“to drink together”) → combibō (“drinking buddy”)

vāpulāre (“to get beaten”) → vāpulō (“who gets frequently flogged”)

?cōci- → cōciō (“broker”)

centuria (“century”) → centuriō (“centurion”)

mūlus (“mule”) → mūliō (“muleteer”)

Ancient Greek μωρός (mōrós, “dull, sluggish”) → mōriō (“idiot”)

Used to form masculine nouns with various meanings:

forms agent nouns, positive and especially negative nicknames and other personal designations, especially in colloquial language.

aquila (“eagle”) → Aquilō (“the North wind”)

incubāre (“to lie on top”) → Incubō (“a spirit that watches over buried treasures”)

cūria (“curia”) → Cūriō

cicer (“chickpea”) → Cicerō

vārus (“bow-legged”) → Varrō

catus (“clever, shrewd”) → Catō

conger (“sea-eel”) → Congriō (“name of a cook in Plautus”)

(Late Latin) also used as an ending for some inanimate nouns.

-ō (canonical masculine)
-ōnis (genitive)
-ō (nominative singular)
-ōnēs (nominative plural)
-ōnis (genitive singular)
-ōnum (genitive plural)
-ōnī (dative singular)
-ōnibus (dative plural)
-ōnem (accusative singular)
-ōnēs (accusative plural)
-ōne (ablative singular)
-ōnibus (ablative plural)
-ō (singular vocative)
-ōnēs (plural vocative)

Franco-Provençal: -on

French: -on
→ English: -oon

Italian: -one

Portuguese: -ão

Romanian: -oi, -oni

Sicilian: -uni, -una

Spanish: -ón

Etymology tree
Proto-Indo-European *-h₃onh₂-der.
Latin -o
From Proto-Indo-European *-h₃onh₂- (with nominative ō made common to all cases). Etymologically, it forms part of the abstract noun suffixes -iō f, -tiō f, -āgō f, -īgō f, -ūgō f, -tūdō f, -ēdō f, but synchronically, these have become differentiated in Latin: abstract nouns in -ō are regularly feminine (and those that end in a consonant + -ō show -in- rather than -ōn- in oblique cases), whereas non-abstract nouns in -ō, -ōnis are typically masculine.


-o

prīmus + -ō → prīmō

tūtus + -ō → tūtō

-ō (canonical)
-ius (comparative)
-issimō (superlative)

From Proto-Italic *-ōd, an ablative suffix, derived from Proto-Indo-European *-éad.


-o

cūra + -ō → cūrō

dōnum + -ō → dōnō

laus (stem: laud-) + -ō → laudō

multa + -ō → multō

nūndinae + -or → nūndinor (deponent)

suffixed to nouns or adjectives — originally a-stem nouns, but later nouns with other stems — forms regular first-conjugation verbs

-ō (canonical)
-āre (infinitive present)
-āvī (active perfect)
-ātum (supine)
-ō (active first-person indicative present singular)
-ās (active indicative present second-person singular)
-at (active indicative present singular third-person)
-āmus (active first-person indicative plural present)
-ātis (active indicative plural present second-person)
-ant (active indicative plural present third-person)
-ābam (active first-person imperfect indicative singular)
-ābās (active imperfect indicative second-person singular)
-ābat (active imperfect indicative singular third-person)
-ābāmus (active first-person imperfect indicative plural)
-ābātis (active imperfect indicative plural second-person)
-ābant (active imperfect indicative plural third-person)
-ābō (active first-person future indicative singular)
-ābis (active future indicative second-person singular)
-ābit (active future indicative singular third-person)
-ābimus (active first-person future indicative plural)
-ābitis (active future indicative plural second-person)
-ābunt (active future indicative plural third-person)
-āvī (active first-person indicative perfect singular)
-āvistī (active indicative perfect second-person singular)
-āstī (active indicative perfect second-person singular)
-āvit (active indicative perfect singular third-person)
-āt (active indicative perfect singular third-person)
-āvimus (active first-person indicative perfect plural)
-āmus (active first-person indicative perfect plural)
-āvistis (active indicative perfect plural second-person)
-āstis (active indicative perfect plural second-person)
-āvērunt (active indicative perfect plural third-person)
-āvēre (active indicative perfect plural third-person)
-ārunt (active indicative perfect plural third-person)
-āveram (active first-person indicative pluperfect singular)
-āram (active first-person indicative pluperfect singular)
-āverās (active indicative pluperfect second-person singular)
-ārās (active indicative pluperfect second-person singular)
-āverat (active indicative pluperfect singular third-person)
-ārat (active indicative pluperfect singular third-person)
-āverāmus (active first-person indicative pluperfect plural)
-ārāmus (active first-person indicative pluperfect plural)
-āverātis (active indicative pluperfect plural second-person)
-ārātis (active indicative pluperfect plural second-person)
-āverant (active indicative pluperfect plural third-person)
-ārant (active indicative pluperfect plural third-person)
-āverō (active first-person future indicative perfect singular)
-ārō (active first-person future indicative perfect singular)
-āveris (active future indicative perfect second-person singular)
-āris (active future indicative perfect second-person singular)
-āverit (active future indicative perfect singular third-person)
-ārit (active future indicative perfect singular third-person)
-āverimus (active first-person future indicative perfect plural)
-ārimus (active first-person future indicative perfect plural)
-āveritis (active future indicative perfect plural second-person)
-āritis (active future indicative perfect plural second-person)
-āverint (active future indicative perfect plural third-person)
-ārint (active future indicative perfect plural third-person)
-āssō (active first-person future sigmatic singular)
-āssis (active future second-person sigmatic singular)
-āssit (active future sigmatic singular third-person)
-āssimus (active first-person future plural sigmatic)
-āssitis (active future plural second-person sigmatic)
-āssint (active future plural sigmatic third-person)
-or (first-person indicative passive present singular)
-āris (indicative passive present second-person singular)
-āre (indicative passive present second-person singular)
-ātur (indicative passive present singular third-person)
-āmur (first-person indicative passive plural present)
-āminī (indicative passive plural present second-person)
-antur (indicative passive plural present third-person)
-ābar (first-person imperfect indicative passive singular)
-ābāris (imperfect indicative passive second-person singular)
-ābāre (imperfect indicative passive second-person singular)
-ābātur (imperfect indicative passive singular third-person)
-ābāmur (first-person imperfect indicative passive plural)
-ābāminī (imperfect indicative passive plural second-person)
-ābantur (imperfect indicative passive plural third-person)
-ābor (first-person future indicative passive singular)
-āberis (future indicative passive second-person singular)
-ābere (future indicative passive second-person singular)
-ābitur (future indicative passive singular third-person)
-ābimur (first-person future indicative passive plural)
-ābiminī (future indicative passive plural second-person)
-ābuntur (future indicative passive plural third-person)
-ātus + future active indicative of sum (future indicative passive perfect)
-āssor (first-person future passive sigmatic singular)
-āsseris (future passive second-person sigmatic singular)
-āssitur (future passive sigmatic singular third-person)
-em (active first-person present singular subjunctive)
-ēs (active present second-person singular subjunctive)
-et (active present singular subjunctive third-person)
-ēmus (active first-person plural present subjunctive)
-ētis (active plural present second-person subjunctive)
-ent (active plural present subjunctive third-person)
-ārem (active first-person imperfect singular subjunctive)
-ārēs (active imperfect second-person singular subjunctive)
-āret (active imperfect singular subjunctive third-person)
-ārēmus (active first-person imperfect plural subjunctive)
-ārētis (active imperfect plural second-person subjunctive)
-ārent (active imperfect plural subjunctive third-person)
-āverim (active first-person perfect singular subjunctive)
-ārim (active first-person perfect singular subjunctive)
-āverīs (active perfect second-person singular subjunctive)
-ārīs (active perfect second-person singular subjunctive)
-āverit (active perfect singular subjunctive third-person)
-ārit (active perfect singular subjunctive third-person)
-āverīmus (active first-person perfect plural subjunctive)
-ārīmus (active first-person perfect plural subjunctive)
-āverītis (active perfect plural second-person subjunctive)
-ārītis (active perfect plural second-person subjunctive)
-āverint (active perfect plural subjunctive third-person)
-ārint (active perfect plural subjunctive third-person)
-āvissem (active first-person pluperfect singular subjunctive)
-āssem (active first-person pluperfect singular subjunctive)
-āvissēs (active pluperfect second-person singular subjunctive)
-āssēs (active pluperfect second-person singular subjunctive)
-āvisset (active pluperfect singular subjunctive third-person)
-āsset (active pluperfect singular subjunctive third-person)
-āvissēmus (active first-person pluperfect plural subjunctive)
-āssēmus (active first-person pluperfect plural subjunctive)
-āvissētis (active pluperfect plural second-person subjunctive)
-āssētis (active pluperfect plural second-person subjunctive)
-āvissent (active pluperfect plural subjunctive third-person)
-āssent (active pluperfect plural subjunctive third-person)
-āssim (active aorist first-person sigmatic singular)
-āssīs (active aorist second-person sigmatic singular)
-āssīt (active aorist sigmatic singular third-person)
-āssīmus (active aorist first-person plural sigmatic)
-āssītis (active aorist plural second-person sigmatic)
-āssint (active aorist plural sigmatic third-person)
-er (first-person passive present singular subjunctive)
-ēris (passive present second-person singular subjunctive)
-ēre (passive present second-person singular subjunctive)
-ētur (passive present singular subjunctive third-person)
-ēmur (first-person passive plural present subjunctive)
-ēminī (passive plural present second-person subjunctive)
-entur (passive plural present subjunctive third-person)
-ārer (first-person imperfect passive singular subjunctive)
-ārēris (imperfect passive second-person singular subjunctive)
-ārēre (imperfect passive second-person singular subjunctive)
-ārētur (imperfect passive singular subjunctive third-person)
-ārēmur (first-person imperfect passive plural subjunctive)
-ārēminī (imperfect passive plural second-person subjunctive)
-ārentur (imperfect passive plural subjunctive third-person)
-ā (active imperative present second-person singular)
-āte (active imperative plural present second-person)
-ātō (active future imperative second-person singular)
-ātō (active future imperative singular third-person)
-ātōte (active future imperative plural second-person)
-antō (active future imperative plural third-person)
-āre (imperative passive present second-person singular)
-āminī (imperative passive plural present second-person)
-ātor (future imperative passive second-person singular)
-ātor (future imperative passive singular third-person)
-antor (future imperative passive plural third-person)
-āre (active imperative infinitive present)
-āvisse (active imperative infinitive perfect)
-āsse (active imperative infinitive perfect)
-ātūrum esse (active future imperative infinitive)
-ārī (imperative infinitive passive present)
-ārier (imperative infinitive passive present)
-ātum esse (imperative infinitive passive perfect)
-ātum īrī (future imperative infinitive passive)
-āns (active imperative participle present)
-ātūrus (active future imperative participle)
-ātus (imperative participle passive perfect)
-andus (future imperative participle passive)
-andī (genitive gerund noun-from-verb)
-andō (dative gerund noun-from-verb)
-andum (accusative gerund noun-from-verb)
-andō (ablative gerund noun-from-verb)
-ātum (accusative noun-from-verb supine)
-ātū (ablative noun-from-verb supine)
-ō (active first-person indicative present singular)
-ās (active indicative present second-person singular)
-at (active indicative present singular third-person)
-āmus (active first-person indicative plural present)
-ātis (active indicative plural present second-person)
-ant (active indicative plural present third-person)
-ābam (active first-person imperfect indicative singular)
-ābās (active imperfect indicative second-person singular)
-ābat (active imperfect indicative singular third-person)
-ābāmus (active first-person imperfect indicative plural)
-ābātis (active imperfect indicative plural second-person)
-ābant (active imperfect indicative plural third-person)
-ābō (active first-person future indicative singular)
-ābis (active future indicative second-person singular)
-ābit (active future indicative singular third-person)
-ābimus (active first-person future indicative plural)
-ābitis (active future indicative plural second-person)
-ābunt (active future indicative plural third-person)
-uī (active first-person indicative perfect singular)
-uistī (active indicative perfect second-person singular)
-uit (active indicative perfect singular third-person)
-uimus (active first-person indicative perfect plural)
-uistis (active indicative perfect plural second-person)
-uērunt (active indicative perfect plural third-person)
-uēre (active indicative perfect plural third-person)
-ueram (active first-person indicative pluperfect singular)
-uerās (active indicative pluperfect second-person singular)
-uerat (active indicative pluperfect singular third-person)
-uerāmus (active first-person indicative pluperfect plural)
-uerātis (active indicative pluperfect plural second-person)
-uerant (active indicative pluperfect plural third-person)
-uerō (active first-person future indicative perfect singular)
-ueris (active future indicative perfect second-person singular)
-uerit (active future indicative perfect singular third-person)
-uerimus (active first-person future indicative perfect plural)
-ueritis (active future indicative perfect plural second-person)
-uerint (active future indicative perfect plural third-person)
-āssō (active first-person future sigmatic singular)
-āssis (active future second-person sigmatic singular)
-āssit (active future sigmatic singular third-person)
-āssimus (active first-person future plural sigmatic)
-āssitis (active future plural second-person sigmatic)
-āssint (active future plural sigmatic third-person)
-or (first-person indicative passive present singular)
-āris (indicative passive present second-person singular)
-āre (indicative passive present second-person singular)
-ātur (indicative passive present singular third-person)
-āmur (first-person indicative passive plural present)
-āminī (indicative passive plural present second-person)
-antur (indicative passive plural present third-person)
-ābar (first-person imperfect indicative passive singular)
-ābāris (imperfect indicative passive second-person singular)
-ābāre (imperfect indicative passive second-person singular)
-ābātur (imperfect indicative passive singular third-person)
-ābāmur (first-person imperfect indicative passive plural)
-ābāminī (imperfect indicative passive plural second-person)
-ābantur (imperfect indicative passive plural third-person)
-ābor (first-person future indicative passive singular)
-āberis (future indicative passive second-person singular)
-ābere (future indicative passive second-person singular)
-ābitur (future indicative passive singular third-person)
-ābimur (first-person future indicative passive plural)
-ābiminī (future indicative passive plural second-person)
-ābuntur (future indicative passive plural third-person)
-ātus + future active indicative of sum (future indicative passive perfect)
-āssor (first-person future passive sigmatic singular)
-āsseris (future passive second-person sigmatic singular)
-āssitur (future passive sigmatic singular third-person)
-em (active first-person present singular subjunctive)
-ēs (active present second-person singular subjunctive)
-et (active present singular subjunctive third-person)
-ēmus (active first-person plural present subjunctive)
-ētis (active plural present second-person subjunctive)
-ent (active plural present subjunctive third-person)
-ārem (active first-person imperfect singular subjunctive)
-ārēs (active imperfect second-person singular subjunctive)
-āret (active imperfect singular subjunctive third-person)
-ārēmus (active first-person imperfect plural subjunctive)
-ārētis (active imperfect plural second-person subjunctive)
-ārent (active imperfect plural subjunctive third-person)
-uerim (active first-person perfect singular subjunctive)
-uerīs (active perfect second-person singular subjunctive)
-uerit (active perfect singular subjunctive third-person)
-uerīmus (active first-person perfect plural subjunctive)
-uerītis (active perfect plural second-person subjunctive)
-uerint (active perfect plural subjunctive third-person)
-uissem (active first-person pluperfect singular subjunctive)
-uissēs (active pluperfect second-person singular subjunctive)
-uisset (active pluperfect singular subjunctive third-person)
-uissēmus (active first-person pluperfect plural subjunctive)
-uissētis (active pluperfect plural second-person subjunctive)
-uissent (active pluperfect plural subjunctive third-person)
-āssim (active aorist first-person sigmatic singular)
-āssīs (active aorist second-person sigmatic singular)
-āssīt (active aorist sigmatic singular third-person)
-āssīmus (active aorist first-person plural sigmatic)
-āssītis (active aorist plural second-person sigmatic)
-āssint (active aorist plural sigmatic third-person)
-er (first-person passive present singular subjunctive)
-ēris (passive present second-person singular subjunctive)
-ēre (passive present second-person singular subjunctive)
-ētur (passive present singular subjunctive third-person)
-ēmur (first-person passive plural present subjunctive)
-ēminī (passive plural present second-person subjunctive)
-entur (passive plural present subjunctive third-person)
-ārer (first-person imperfect passive singular subjunctive)
-ārēris (imperfect passive second-person singular subjunctive)
-ārēre (imperfect passive second-person singular subjunctive)
-ārētur (imperfect passive singular subjunctive third-person)
-ārēmur (first-person imperfect passive plural subjunctive)
-ārēminī (imperfect passive plural second-person subjunctive)
-ārentur (imperfect passive plural subjunctive third-person)
-ā (active imperative present second-person singular)
-āte (active imperative plural present second-person)
-ātō (active future imperative second-person singular)
-ātō (active future imperative singular third-person)
-ātōte (active future imperative plural second-person)
-antō (active future imperative plural third-person)
-āre (imperative passive present second-person singular)
-āminī (imperative passive plural present second-person)
-ātor (future imperative passive second-person singular)
-ātor (future imperative passive singular third-person)
-antor (future imperative passive plural third-person)
-āre (active imperative infinitive present)
-uisse (active imperative infinitive perfect)
-ātūrum esse (active future imperative infinitive)
-ārī (imperative infinitive passive present)
-ārier (imperative infinitive passive present)
-ātum esse (imperative infinitive passive perfect)
-ātum īrī (future imperative infinitive passive)
-āns (active imperative participle present)
-ātūrus (active future imperative participle)
-ātus (imperative participle passive perfect)
-andus (future imperative participle passive)
-andī (genitive gerund noun-from-verb)
-andō (dative gerund noun-from-verb)
-andum (accusative gerund noun-from-verb)
-andō (ablative gerund noun-from-verb)
-ātum (accusative noun-from-verb supine)
-ātū (ablative noun-from-verb supine)

Asturian: -ar

Catalan: -ar

Italian: -are

Franco-Provençal: -ar

Friulian: -â

Occitan: -ar

desctree

Old French: -er, -ier
Middle French: -er
French: -er
Gallo: -ieu
→ Middle High German: -ieren
German: -ieren, -iren (obsolete, used alternatively until ca. 1900)
→ Bulgarian: -ирам (-iram)
→ Russian: -ировать (-irovatʹ)
→ Serbo-Croatian: -irati
Norman: -yi (Jersey)

Old Galician-Portuguese: -ar

Galician: -ar

Portuguese: -ar

Romanian: -a

Sardinian: -are

Sicilian: -ari

Spanish: -ar

Borrowings:

→ English: -ate

→ Ido: -ar

From Proto-Italic *-āō, from denominative verbs with *-eh₂-yé-ti, in which the first person singular ends in *-eh₂-yóh₂ > intermediate phase **-ājō with accent shift > Proto-Italic *-āō (e.g., laudō, dōnō, pugnō, cūrō). Cognates of the whole first conjugation in the present in Latin and Proto-Italic include Proto-Germanic *-ōną (referring to the whole conjugation in which the infinitive is *-ōną), Ancient Greek -άω (-áō, contracted verb), -अयति (-ayati) (for the causative in Sanskrit), Proto-Celtic *-āti and Proto-Balto-Slavic *-ā́ˀtei (whence the infinite Proto-Slavic *-ati, referring again to the whole conjugation).
Etymologically, this denominative suffix was not used to form all first-conjugation verbs. It can be distinguished in origin from the following types that happened to fall together with it phonetically:
* Verbs from roots in *-h₁- (e.g. flō).
* Verbs from roots in *-h₂- (e.g. for, nō, hiō, domō, iuvō).
* Verbs from roots in *-h₃- (e.g. dō, lavō, arō).
* In one exceptional case, by sound laws acting on *-h₂ + stative suffix *-éh₁-ye-ti, whence *-h₂-éh₁-ye-ti. This case is the verb stō: *sth₂-éh₁-ye-ti > *staēō > stō).


-o

com- + pellō (pres. act. inf.: pellere) + -ō → compellō (pres. act. inf.: compellāre)

prō- + flīgō (pres. act. inf.: flīgere) + -ō → prōflīgō (pres. act. inf.: prōflīgāre)

suffixed to third-conjugation verbs in composition, forms regular first-conjugation verbs

-ō (canonical)
-āre (infinitive present)
-āvī (active perfect)
-ātum (supine)

Some third-conjugation verbs show a shift to the first declension in composition, such as pellō, pellere vs. -pellō, -pellāre (in compellō, compellāre and interpellō, interpellāre) or sternō, sternere vs. cōnsternō, cōnsternāre. Schrijver (1991) derives the simplex third-conjugation versions from nasal presents in *-n-H-ti of the type *tl-n-h₂-ti > *tl̥năti > tollit (arguing that Proto-Indo-European present forms in *-né-H-ti, showing the full grade of the suffix, were replaced by paradigmatic leveling) and proposes that the compounds were derived by addition of the thematic suffix *-ye-/-yo- to *-nă-, forming *-năye-/-năyo-. In this case, the Proto-Italic form would be *-aō. Traditionally, these compound verbs in -āre were explained as "intensive" forms alongside cases like occupō, occupāre, but Schrijver argues that the latter are clearly denominative while the former are clearly not.


-o

-ō (canonical)
-ere (infinitive present)
-ī (active perfect)
-um (supine)
-ō (active first-person indicative present singular)
-is (active indicative present second-person singular)
-it (active indicative present singular third-person)
-imus (active first-person indicative plural present)
-itis (active indicative plural present second-person)
-unt (active indicative plural present third-person)
-ēbam (active first-person imperfect indicative singular)
-ēbās (active imperfect indicative second-person singular)
-ēbat (active imperfect indicative singular third-person)
-ēbāmus (active first-person imperfect indicative plural)
-ēbātis (active imperfect indicative plural second-person)
-ēbant (active imperfect indicative plural third-person)
-am (active first-person future indicative singular)
-ēs (active future indicative second-person singular)
-et (active future indicative singular third-person)
-ēmus (active first-person future indicative plural)
-ētis (active future indicative plural second-person)
-ent (active future indicative plural third-person)
-ī (active first-person indicative perfect singular)
-istī (active indicative perfect second-person singular)
-it (active indicative perfect singular third-person)
-imus (active first-person indicative perfect plural)
-istis (active indicative perfect plural second-person)
-ērunt (active indicative perfect plural third-person)
-ēre (active indicative perfect plural third-person)
-eram (active first-person indicative pluperfect singular)
-erās (active indicative pluperfect second-person singular)
-erat (active indicative pluperfect singular third-person)
-erāmus (active first-person indicative pluperfect plural)
-erātis (active indicative pluperfect plural second-person)
-erant (active indicative pluperfect plural third-person)
-erō (active first-person future indicative perfect singular)
-eris (active future indicative perfect second-person singular)
-erit (active future indicative perfect singular third-person)
-erimus (active first-person future indicative perfect plural)
-eritis (active future indicative perfect plural second-person)
-erint (active future indicative perfect plural third-person)
-ō (active first-person future sigmatic singular)
-is (active future second-person sigmatic singular)
-it (active future sigmatic singular third-person)
-imus (active first-person future plural sigmatic)
-itis (active future plural second-person sigmatic)
-int (active future plural sigmatic third-person)
-or (first-person indicative passive present singular)
-eris (indicative passive present second-person singular)
-ere (indicative passive present second-person singular)
-itur (indicative passive present singular third-person)
-imur (first-person indicative passive plural present)
-iminī (indicative passive plural present second-person)
-untur (indicative passive plural present third-person)
-ēbar (first-person imperfect indicative passive singular)
-ēbāris (imperfect indicative passive second-person singular)
-ēbāre (imperfect indicative passive second-person singular)
-ēbātur (imperfect indicative passive singular third-person)
-ēbāmur (first-person imperfect indicative passive plural)
-ēbāminī (imperfect indicative passive plural second-person)
-ēbantur (imperfect indicative passive plural third-person)
-ar (first-person future indicative passive singular)
-ēris (future indicative passive second-person singular)
-ēre (future indicative passive second-person singular)
-ētur (future indicative passive singular third-person)
-ēmur (first-person future indicative passive plural)
-ēminī (future indicative passive plural second-person)
-entur (future indicative passive plural third-person)
-us + present active indicative of sum (indicative passive perfect)
-us + future active indicative of sum (future indicative passive perfect)
-or (first-person future passive sigmatic singular)
-eris (future passive second-person sigmatic singular)
-itur (future passive sigmatic singular third-person)
-am (active first-person present singular subjunctive)
-ās (active present second-person singular subjunctive)
-at (active present singular subjunctive third-person)
-āmus (active first-person plural present subjunctive)
-ātis (active plural present second-person subjunctive)
-ant (active plural present subjunctive third-person)
-erem (active first-person imperfect singular subjunctive)
-erēs (active imperfect second-person singular subjunctive)
-eret (active imperfect singular subjunctive third-person)
-erēmus (active first-person imperfect plural subjunctive)
-erētis (active imperfect plural second-person subjunctive)
-erent (active imperfect plural subjunctive third-person)
-erim (active first-person perfect singular subjunctive)
-erīs (active perfect second-person singular subjunctive)
-erit (active perfect singular subjunctive third-person)
-erīmus (active first-person perfect plural subjunctive)
-erītis (active perfect plural second-person subjunctive)
-erint (active perfect plural subjunctive third-person)
-issem (active first-person pluperfect singular subjunctive)
-issēs (active pluperfect second-person singular subjunctive)
-isset (active pluperfect singular subjunctive third-person)
-issēmus (active first-person pluperfect plural subjunctive)
-issētis (active pluperfect plural second-person subjunctive)
-issent (active pluperfect plural subjunctive third-person)
-im (active aorist first-person sigmatic singular)
-īs (active aorist second-person sigmatic singular)
-īt (active aorist sigmatic singular third-person)
-īmus (active aorist first-person plural sigmatic)
-ītis (active aorist plural second-person sigmatic)
-int (active aorist plural sigmatic third-person)
-ar (first-person passive present singular subjunctive)
-āris (passive present second-person singular subjunctive)
-āre (passive present second-person singular subjunctive)
-ātur (passive present singular subjunctive third-person)
-āmur (first-person passive plural present subjunctive)
-āminī (passive plural present second-person subjunctive)
-antur (passive plural present subjunctive third-person)
-erer (first-person imperfect passive singular subjunctive)
-erēris (imperfect passive second-person singular subjunctive)
-erēre (imperfect passive second-person singular subjunctive)
-erētur (imperfect passive singular subjunctive third-person)
-erēmur (first-person imperfect passive plural subjunctive)
-erēminī (imperfect passive plural second-person subjunctive)
-erentur (imperfect passive plural subjunctive third-person)
-us + present active subjunctive of sum (passive perfect subjunctive)
-e (active imperative present second-person singular)
-ite (active imperative plural present second-person)
-itō (active future imperative second-person singular)
-itō (active future imperative singular third-person)
-itōte (active future imperative plural second-person)
-untō (active future imperative plural third-person)
-ere (imperative passive present second-person singular)
-iminī (imperative passive plural present second-person)
-itor (future imperative passive second-person singular)
-itor (future imperative passive singular third-person)
-untor (future imperative passive plural third-person)
-ere (active imperative infinitive present)
-isse (active imperative infinitive perfect)
-ūrum esse (active future imperative infinitive)
-ī (imperative infinitive passive present)
-um esse (imperative infinitive passive perfect)
-um īrī (future imperative infinitive passive)
-ēns (active imperative participle present)
-ūrus (active future imperative participle)
-us (imperative participle passive perfect)
-endus (future imperative participle passive)
-undus (future imperative participle passive)
-endī (genitive gerund noun-from-verb)
-endō (dative gerund noun-from-verb)
-endum (accusative gerund noun-from-verb)
-endō (ablative gerund noun-from-verb)
-um (accusative noun-from-verb supine)
-ū (ablative noun-from-verb supine)

From Proto-Italic *-ō, from at least two sources:
# Proto-Indo-European thematic *-e-ti in which the first person singular ends in *-oh₂ (e.g., agō < *h₂éǵeti; coquo < *pékʷeti).
# Proto-Indo-European athematic *-ti, in which the first person singular ends in *-mi (e.g., dūcō < *déwkti; edō < *h₁édti; linquō < *linékʷti; discō < *di-dḱ-ské-ti).


-o

dative/ablative masculine/neuter singular of -us

Dative from Old Latin -ōi, from Proto-Italic *-ōi, from Proto-Indo-European *-oey.
Ablative from Old Latin -ōd.


-o

Aplis m + -o → Aplo f

Baezus m + -o → Baezo f

Dasant- m + -o → Dasto f

Ditus m + -o → Dito f

Paius m + -o → Paio f

Vendes m + -o → Vendo f

form feminine equivalents of given names of central Dalmatia

-ō (canonical feminine)
-ōnis (genitive)

Borrowed from Paleo-Balkan. Compare Albanian -ónjë, Aromanian -oanje, -oanji, -onje and Romanian -oaie, all forming feminine equivalent of nouns.