Thomas Aquinas

On the Activities of Angels

Latin Grammar: Fourth Declension Nouns

Manifestum est autem quod apparitiones imaginariae causantur interdum in nobis ex locali mutatione corporalium spirituum et humorum.

Fourth declension nouns are characterized by -u-.  The number of fourth declension nouns is relatively small, but both masculine and feminine fourth declension nouns, which end in -us, resemble second declension nouns in the nominative as well as some third declension nouns.  Neuters, however, do not present this problem because the nominative ends in -u.  Nevertheless, this reinforces the importance of memorizing a noun's genitive along with its nominative to be able to distinguish second declension (genitive in -i), third declension (genitive in -is), and fourth declension (genitive in -us) nouns. 

Practice declining fourth declension nouns by translating the following English phrases into Latin.

1. by [means of] my hands:

2. to/for my hand:

3. into my house: in

4. into our houses: in

5. two horns:

6. the nature of a horn:

7. the nature of horns:

8. two fruits:

9. the nature of a fruit:

10. the nature of fruits:

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