Caerus Latin

4th & 5th Declension Nouns

The 4th and 5th declensions are rarer than the first three but appear regularly in GCSE texts. Learn the key endings and you will recognise them instantly.

Fourth Declension

4th declension nouns are mostly masculine and end in -us in the nominative singular. The stem vowel is -u-, which appears in most endings.

Formation rules

  • Nominative singular: -us (e.g. manus = hand)
  • Genitive singular: -ūs (long u — do not confuse with the nominative)
  • Dative singular: -uī
  • Accusative singular: -um
  • Ablative singular: -ū (long u)
  • Nominative/accusative plural: -ūs
  • Dative/ablative plural: -ibus (same as 3rd declension!)

Worked examples

Mīlitēs manibus pugnābant. — The soldiers were fighting with their hands. (manibus = ablative plural, means)

Fīlius manūs patris tenēbat. — The son was holding the hands of his father. (manūs = accusative plural)

Fifth Declension

5th declension nouns are mostly feminine and end in -ēs in the nominative singular. The most common is rēs (thing, matter) — it appears constantly in Latin texts.

Formation rules

  • Nominative/vocative singular: -ēs
  • Accusative singular: -em
  • Genitive/dative singular: -eī
  • Ablative singular: -ē
  • Nominative/vocative/accusative plural: -ēs (all three the same!)
  • Genitive plural: -ērum
  • Dative/ablative plural: -ēbus

Worked examples

Senex dē rē cogitābat. — The old man was thinking about the matter. (rē = ablative singular after dē)

Multās rēs in forō vīdimus. — We saw many things in the forum. (rēs = accusative plural)

Exam tip: The trickiest forms are the 4th declension genitive singular (manūs) and nominative plural (manūs) — they look identical. Use context: if it follows a noun as a possessive it is genitive; if it is the subject of the verb it is nominative. For the 5th declension, watch for reī (genitive/dative) — two syllables, long -ī.

Practice