Latin Nouns: Fourth Declension ŭ-stem

Endings for ŭ-stem Nouns


Case Singular Plural
Nominative -us -ūs
Genitive -ūs -uum
Dative -uī -ibus
Accusative -um -ūs
Vocative -us
Ablative -ibus


  Singular Plural
Nominative -ua
Genitive -ūs -uum
Dative -ibus
Accusative -ua
Vocative -ua
Ablative -ibus


fructus, fructūs (m), fruit
Case Singular Plural
nom. fructus fructūs
gen. fructūs fructuum
dat. fruct fructibus
acc. fructum fructūs
voc. fructus fructūs
abl. fructū fructibus
cornū, cornū (n), horn, wing of an army
Case Singular Plural
nom. cornū cornua
gen. cornūs cornuum
dat. cornū cornibus
acc. cornū cornua
voc. cornū cornua
abl. cornū cornibus

Additional Notes

Odds and Ends

  • Almost all nouns in the fourth declension are masculine instead of feminine. Some exceptions are acus (needle), domus (house), manus (house), tribus (tribe), porticus (colonnade (array of columns)), and Idus (Ides). Trees, by gender rules mentioned in other declensions, also override the noun’s gender as feminine.
  • In early Latin, ū-stem nouns can take the genitive singular form of -ī.
  • Only three commonly used neuter nouns exist in the fourth declension: cornu (horn, wing of an army), genu (knee), and veru (spirit).
  • Artus, tribus, and fourth declension nouns ending in -cus tend to take the dative and ablative plural form of -ubus instead of -ibus.
  • Some fourth declension nouns can take the dative singular ending instead of -uī.

The Domus Problem

Domus (home) cannot decide whether or not it wants to be in the fourth declension or the second declension. While it is classified as fourth declension (or irregular), the following inflections follow the second declension ŏ-stem pattern:

  • locative singular: domi
  • ablative singular: domo
  • accusative singular: domum
  • accusative plural: domos

Recommended Latin Grammar Reading