Etymology and origin of the Latin word -o
-o1 nouns of agent, -ōnis
- Confidence
- Probable
- Formation
- Inherited
- First attested
- c. 250–184 BC Plautus
- Inherited from
- Proto-Indo-European *-ō
- Ultimate origin
- Proto-Indo-European *-ō
Pronunciation
Forms
-ō m (genitive -ōnis); third declension[2][1]
Etymology
The suffix for nouns of agent and for names is inherited from Proto-Indo-European *-ō, oblique *-on-, perhaps merged with “Hoffmann's suffix” *-h₃ō, a connection Wiktionary calls controversial.[1] Fortson describes an individualizing suffix of this shape in the parent language, added to adjectives to make words for “the one that is X”, and finds it in Latin names such as Catō, “the one who is clever”, from catus.[3] Weiss explains the cognomen Nerō, originally Sabellic, in the same way, as “the man, the manly one”.[4]
Latin spread the long vowel of the nominative through the whole paradigm,[1][5] so that most non-neuter n-stems have -ōnis in the genitive.[5]
Earliest recorded meaning
Plautus already has nouns of this class for people and things, such as caupō “innkeeper” and carbō “a piece of charcoal”.[2][5]
Semantic evolution
The class was large and productive enough to take in loanwords, among them sīpō from Greek and sāpō from a Germanic source.[5] Its nouns for people are often colloquial or pejorative, and those made from nouns include nicknames for someone with a prominent feature and words for a dealer or worker in something.[1] It also supplied many cognomina,[1][2] and in Late Latin it was added to some nouns for inanimate things.[1]
Timeline
- c. 250–184 BC – Plautus uses caupō and carbō.[2][6]
- 81–43 BC – Cicero names the consul Varrō who commanded at Cannae.[2][6]
Meanings
Suffix
- Forms masculine nouns of agent from verbs: combibō, incubō.[2][1]
- Forms personal names, especially cognomina, from nouns: Cicerō, Varrō.[2][1]
- (Late Latin) An ending added to some nouns for inanimate things.[1]
Word family
-o2 adverbs
- Confidence
- Probable
- Formation
- Inherited
- First attested
- c. 250–184 BC Plautus
- Inherited from
- Proto-Italic *-ōd
- Ultimate origin
- Proto-Italic *-ōd
Pronunciation
Forms
Etymology
The suffix for adverbs is inherited from Proto-Italic *-ōd, an ablative ending, which Wiktionary derives from Proto-Indo-European *-éad.[1] The OLD and Weiss regard these adverbs as ablative singulars of nouns and of second- and first-declension adjectives,[2][4] and Weiss compares Oscan contrud.[4] Sihler notes that some of them may instead continue an instrumental *-oH₁.[5]
Earliest recorded meaning
Inscriptions print the older form with final -d, ⟨meritod⟩ and ⟨meretod⟩,[2] and Plautus already has prīmō “at first”.[2]
Semantic evolution
What began as a modal ablative of nouns came to be felt as an adverb.[2] Weiss lists it beside the regular adverbs in -ē as the ending some adjectives of these declensions use, as in crēbrō, continuō and meritō.[4]
Timeline
Meanings
Suffix
Word family
-o3 first-conjugation verbs
- Confidence
- Established
- Formation
- Inherited
- First attested
- c. 250–184 BC Plautus
- Inherited from
- Proto-Italic *-āō
- Ultimate origin
- Proto-Indo-European *-eh₂-yé-ti
Pronunciation
Forms
-ō (present infinitive -āre, perfect active -āvī, supine -ātum); first conjugation[2][1]
Etymology
The suffix for denominative verbs of the first conjugation is inherited from Proto-Italic *-āō,[1] which continues the denominative type Proto-Indo-European *-eh₂-yé-ti, with first person singular *-eh₂-yóh₂;[1] Sihler writes the type *-eH₂-yᵉ/o-.[5] Wiktionary compares Proto-Germanic *-ōną, Ancient Greek -άω (-áō), Sanskrit -अयति (-ayati) and Proto-Celtic *-āti,[1] and Sihler the factitives in Hittite -aḫ-ḫ-.[5]
Not every verb in -āre has this source: other types fell together with it.[1] Schrijver, as Wiktionary reports him, derives compounds such as compellō2 from a thematized nasal present, against the traditional view that they were intensives.[1]
Earliest recorded meaning
Plautus already has dōnō “present with”,[2] and Ennius has laudō “praise”.[2]
Semantic evolution
The type began with ā-stem nouns, some o-stems and factitives from adjectives,[5] such as cūrō from cūra and novō from novus.[5] In the earliest known Latin it is already built on stems of every kind, as in laudō from laus, nōminō from nōmen and generō from genus.[5] Sihler calls it the most productive denominative type of Italic.[5]
Timeline
Meanings
Suffix
- Forms denominative verbs of the first conjugation from nouns and adjectives, originally from stems in -a: cūrō, multō2, then from other stems: dōnō, laudō.[2][1]
- Forms first-conjugation compounds from verbs of the third conjugation: compellō2, prōflīgō.[2][1]
Word family
Usage notes
Wiktionary also lists an unproductive -ō, -inis, with short -i- from ablaut, which survives as the last part of -tūdō and -ēdō and in virgō, margō and cardō.[1] It treats the ending of most third-conjugation verbs, as in dūcō, as a separate -ō, the inherited first person singular.[1] Feminine names of central Dalmatia have a further -ō, which it calls a borrowing from Paleo-Balkan.[1]
References
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z 27 28 29 Wiktionary, the free dictionary, https://en.wiktionary.org
- ^ a b c d e f g h i j k l m n o p q r s t u Glare, P. G. W., ed. (2012), Oxford Latin Dictionary, 2nd ed., Oxford: Oxford University Press
- ^ Fortson, Benjamin W., IV (2010), Indo-European Language and Culture: An Introduction, 2nd ed., Malden, MA / Oxford: Wiley-Blackwell
- ^ a b c d Weiss, Michael (2020), Outline of the Historical and Comparative Grammar of Latin, 2nd ed., Ann Arbor: Beech Stave
- ^ a b c d e f g h i j k Sihler, Andrew L. (1995), New Comparative Grammar of Greek and Latin, New York: OUP
- ^ a b c d e Köbler, Gerhard (2010), Lateinisches Abkunfts- und Wirkungswörterbuch für Altertum und Mittelalter, online ed., koeblergerhard.de
Related etymologies
Cite this entry
“-o.” Etymologically, 6 Nov. 2026, etymologically.com/la/-o. Accessed 6 Nov. 2026.
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