GALEAE
[ LESSON XII]
NOUNS IN -IUS AND -IUM
[87.] Nouns of the second declension in -ius and -ium end in -ī in the genitive singular, not in -iī, and the accent rests on the penult; as, fīlī from fīlius (son), praesi´dī from praesi´dium (garrison).
[88.] Proper names of persons in -ius, and fīlius, end in -ī in the vocative singular, not in -ĕ, and the accent rests on the penult; as, Vergi´lī, O Vergil; fīlī, O son.
a. Observe that in these words the vocative and the genitive are alike.
[89.] praesidium (base praesidi-), n., garrison fīlius (base fīli-), m., son
| Singular | |||
|---|---|---|---|
| Nom. | praesidium | fīlius | |
| Gen. | praesi´dī | fīlī | |
| Dat. | praesidiō | fīliō | |
| Acc. | praesidium | fīlium | |
| Abl. | praesidiō | fīliō | |
| Voc. | praesidium | fīlī | |
The plural is regular. Note that the -i- of the base is lost only in the genitive singular, and in the vocative of words like fīlius.