-us

Etymology 1

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.

Pronunciation

• (Classical) IPA^(key): /us/, [ʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /us/, [us]

Suffix

-us

1. suffix of nouns in the second declension.
   1. (chiefly) nominative singular of -us
   2. (uncommon) nominative/accusative/vocative singular of -us for second-declension neuter nouns.

      vīrus; vulgus; pelagus ― rammish smell; common people, crowd; sea

2. suffix of adjectives in the first/second declension.
   1. (chiefly) nominative singular of -us
3. (New Latin) suffix used to Latinize names ending in consonants.

Declension

Second-declension noun forms

Adjective forms

Derived terms

Latin terms suffixed with -us

Etymology 2

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.

Pronunciation

• (Classical) IPA^(key): /us/, [ʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /us/, [us]

Suffix

-us

1. ending of some neuter nouns in the third declension.
   1. nominative/accusative/vocative singular of -us

Declension

Third-declension noun forms

Descendants

• Romanian: -uri (from the plural -ora, with the final vowel replaced due to analogy with feminine plural forms)

Etymology 3

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).

Pronunciation

• (Classical) IPA^(key): /us/, [ʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /us/, [us]

Suffix

-us

1. nominative/vocative singular of -us for nouns in the fourth declension.

Declension

Fourth-declension noun forms

Suffix

-ūs

1. nominative/vocative plural of -us for fourth-declension nouns.
2. genitive singular of -us for fourth-declension nouns.
3. accusative plural of -us for fourth-declension nouns.

See also

• -tus

References

• “-us” on page 2,108/2 of the Oxford Latin Dictionary (1st ed., 1968–82)