-us¹

Meaning

1. morphemeneuternominative/accusative/vocative singular ending of some neuter nouns in the third declension

Origins

Generally from Proto-Indo-European *-os (suffix forming neuter s-stem nouns from verbs), as in genus n from *ǵénh₁os n (“race”). Not a productive derivational suffix in historical Latin. (However, De Vaan cites pondus n and possibly vellus n as formations that may date to a prehistoric stage of the Latin language.) The plural and oblique case forms have -r- as the result of the sound change of rhotacism. Additionally, in many words, the oblique stem has the vowel -ĕ- (as in generis), which is generally taken to be the phonetically regular development of the Proto-Indo-European forms. Some words, such as decus, decoris, instead have -ŏ- in the oblique stem; this is the result of analogical introduction of the rounded vowel from the nominative/accusative singular form.

Meaning

1. commonfemininemasculinemorphemeneuterused as a derivational suffix to form compound agent nouns
   piscis (“fish”) + capiō (“to grasp, catch”) + -us → piscicapus (“a fishcatcher, fisher”)
   via (“road; way”) + cūrō (“to take care”) + -us → viocūrus (“a road overseer”)
2. New Latinfemininemasculinemorphemeneuterused to Latinize names (generally male) that end in consonants
   Kepler + -us → Keplerus
3. femininemasculinemorphemeneuterrareusual nominative singular ending of second declension feminine nouns
4. femininemasculinemorphemeneuterrarenominative/accusative singular ending of a handful of second declension neuter nouns
   vīrus (“a poisonous or acrid secretion”); vulgus (“common people”); pelagus (“sea”)

Origins

From Old Latin and Archaic Latin -os, from Proto-Italic *-os, from Proto-Indo-European *-os (adjectival ending). Cognate with Ancient Greek -ος (-os), Proto-Germanic *-az, Icelandic -ur, Sanskrit -अः (-aḥ), Proto-Slavic *-ъ.

Meaning

1. morphemesuffixderives adjectives (often compound) with a sense like "having (noun)"; most productive in New Latin
   Near-synonym: -ātus
   bī- (“two”) + hiems (“winter”) + -us → bīmus (“two-year-old”)
2. morphemeraresuffixderives relational adjectives
   Hibēr (“Iberian”, noun) + -us → Hibērus (“Iberian”, adjective)
   Marōnēa (“the Thracian city of Maronea”) + -us → Marōnēus (“Maronean; of Maronea”)
3. morphemesuffix-ing: suffixed to verb stems, derives adjectives (often compound) with a sense like "doing/that does (verb)"
   invideō (“to be jealous of, envy; to look askance at (someone)”) + -us → invidus (“envious; hostile”)
   sonō (“to sound”) + -us → -sonus (“-sounding”)

Origins

From Old Latin and Archaic Latin -os, from Proto-Italic *-os, from Proto-Indo-European *-os (adjectival ending). Cognate with Ancient Greek -ος (-os), Proto-Germanic *-az, Icelandic -ur, Sanskrit -अः (-aḥ), Proto-Slavic *-ъ.

Meaning

1. morphemegenitive singular ending of nouns in the fourth declension
2. morphemenominative/vocative plural ending of non-neuter nouns in the fourth declension
3. morphemeaccusative plural ending of non-neuter nouns in the fourth declension

Origins

Not a single suffix, but an ending of various miscellaneous origins. In most fourth-declension words, the final -us evolved from Old Latin -us, from Proto-Italic *-us, from Proto-Indo-European *-us as the final part of Proto-Indo-European *-tus (suffix deriving action nouns from verb roots).

Related words

Meaning

1. femininemasculinemorphemenominative/vocative singular ending of non-neuter nouns in the fourth declension

Origins

Not a single suffix, but an ending of various miscellaneous origins. In most fourth-declension words, the final -us evolved from Old Latin -us, from Proto-Italic *-us, from Proto-Indo-European *-us as the final part of Proto-Indo-European *-tus (suffix deriving action nouns from verb roots).

Meaning

1. morphemerarealternative genitive singular ending for nouns of the third declension
   homō̆ + -us → hominus
   Kastor + -us → Kastorus

Origins

From Proto-Indo-European *-os, a genitive singular ending for athematic nouns (an o-grade alternative to e-grade *-es, which developed to the usual Latin third-declension genitive singular ending -is).