-us
From Old 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.
-us
- suffix of nouns in the second declension.
- (chiefly) nominative singular of -us
- (uncommon) nominative/accusative/vocative singular of -us for second-declension neuter nouns.
- suffix of adjectives in the first/second declension.
- (chiefly) nominative singular of -us
- (New Latin) suffix used to Latinize names ending in consonants.
| Second-declension noun forms |
|---|
| Adjective forms |
|---|
Generally from Proto-Indo-European *-os (suffix forming neuter s-stem nouns from verbs), as in genus n from Proto-Indo-European*ǵénh₁os n (“race”). Not a productive derivational suffix in Latin. 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 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.
-us
- ending of some neuter nouns in the third declension.
- nominative/accusative/vocative singular of -us
| Third-declension noun forms |
|---|
- Romanian: -uri (from the plural -ora, with the final vowel replaced due to analogy with feminine plural forms)[1][2]
Not a single suffix, but an ending of various miscellaneous origins. In most words, 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).
-us
- nominative/vocative singular of -us for nouns in the fourth declension.
| Fourth-declension noun forms |
|---|
-ūs
- nominative/vocative plural of -us for fourth-declension nouns.
- genitive singular of -us for fourth-declension nouns.
- accusative plural of -us for fourth-declension nouns.
- “-us” on page 2,108/2 of the Oxford Latin Dictionary (1st ed., 1968–82)