Appendix:Latin second declension


Latin words of the second declension are generally of masculine gender (ending in -us) or neuter gender (ending in -um), and have a genitive in .

Latin words borrowed from Ancient Greek’s second declension are inflected with a varying mixture of Greek and Latin endings.


Case -us, -ī (m) stem in
-r/-er (m)
-um, -ī (n)
nominative -us -um
genitive -ī ‡¹
accusative -um
vocative -e / ~ī ‡² -um
Case Plural
nominative -a
genitive -ōrum
dative -īs
accusative -ōs -a
ablative -īs
vocative -a
locative -īs


  • ‡¹ In antique Latin, words ending in -ius or -ium take the ending in genitive singular. E.g. in antique times, fīlius became fīlī in the genitive singular (later and nowadays fīliī), and negōtium became negōtī (later and nowadays negōtiī).
  • ‡² * Words ending in -ius and -ium becomes ī. E.g. fīlius becomes fīlī in vocative singular.



  • The singular vocative of second declension -us nouns is the only place in pure Latin words in which the vocative ever differs from the nominative forms: -e instead of -us. The plural vocative is the same as the nominative. As seen in filius, filiī, the vocative singular changes the -ius into an -ī, instead of changing the -us into an -e.
  • deus, -ī m has several irregular plural forms.

Greek declensionEdit

Greek declension
Case Singular Plural
-os/ -us m or f -on/ -um n
nominative -os/ -us -on/ -um -a
genitive -ōrum
dative -īs
accusative -on/ -um -ōs -a
ablative -īs
vocative -e -on/ -um -a
locative -īs



  • Genitive, dative, ablative, locative and usually also the plural are the same as in Latin words; for -os/-us it is like Latin -us and words with stem in r/er, and for -on/-um it is like Latin -um.
  • In case of proper nouns and book titles genitive plural -ōn and nominative plural -oe can appear, as in Vergil's Georgicon Libri alias Georgica and in Terence' Adelphoe.

See alsoEdit