4.2.1. First Declension

1. The Stem of nouns of the First Declension ends in -i, -u, -i, -u and diphthong. The Nominative ending is -s.

2. Europaio nouns of the First Declension are thus generally declined:

3. The animates in -i and -u are masculine or feminine (indifferent to the distinction in adjectives); those in -i and -u, always feminine.

4. The -s can indicate Nominative and Genitive: the distinction is obtained through the full-grade of the vowel before the declension (Gen. -ei-s for -i, -ou-s for -u).

Another problem is that of the indistinctness between the Vocative of the animates and the Nom.-Acc.-Voc. of the inanimates. But in this case, distinction is guaranteed in the noun because they have different stem vowels. The problem comes in the adjective, where a Vocative singular animate -i can be an homophone with Nom.-Acc.-Voc. singular neuter -i (like in lat. suaue, -i). This is, though, a rare case, in which the context is generally enough for disambiguation.