ŏ-Stems.
[23]. Pure Latin nouns of the Second Declension end in -us, -er, -ir, Masculine; -um, Neuter. Originally -us in the Nominative of the Masculine was -os; and -um of the Neuters -om. So also in the Accusative.
Nouns in -us and -um are declined as follows:—
| Hortus, garden; stem, hortŏ-. | Bellum, war; stem, bellŏ-. | |||
| SINGULAR. | ||||
| TERMINATION. | TERMINATION. | |||
| Nom. | hortus | -us | bellum | -um |
| Gen. | hortī | -ī | bellī | -ī |
| Dat. | hortō | -ō | bellō | -ō |
| Acc. | hortum | -um | bellum | -um |
| Voc. | horte | -e | bellum | -um |
| Abl. | hortō | -ō | bellō | -ō |
PLURAL. | ||||
| Nom. | hortī | -ī | bella | -a |
| Gen. | hortōrum | -ōrum | bellōrum | -ōrum |
| Dat. | hortīs | -īs | bellīs | -īs |
| Acc. | hortōs | -ōs | bella | -a |
| Voc. | hortī | -ī | bella | -a |
| Abl. | hortīs | -īs | bellīs | -īs |
Nouns in -er and -ir are declined as follows:—
| Puer, boy; stem, puerŏ- | Ager, field; stem, agrŏ- | Vir, man; stem, virŏ- | ||
| SINGULAR. | TERMINATION. | |||
| Nom. | puer | ager | vir | Wanting |
| Gen. | puerī | agrī | virī | -ī |
| Dat. | puerō | agrō | virō | -ō |
| Acc. | puerum | agrum | virum | -um |
| Voc. | puer | ager | vir | Wanting |
| Abl. | puerō | agrō | virō | -ō |
PLURAL. | ||||
| Nom. | puerī | agrī | virī | -ī |
| Gen. | puerōrum | agrōrum | virōrum | -ōrum |
| Dat. | puerīs | agrīs | virīs | -īs |
| Acc. | puerōs | agrōs | virōs | -ōs |
| Voc. | puerī | agrī | virī | -ī |
| Abl. | puerīs | agrīs | virīs | -īs |
1. Note that in words of the type of puer and vir the final vowel of the stem has disappeared in the Nominative and Vocative Singular.
In the Nominative and Vocative Singular of ager, the stem is further modified by the development of e before r.
2. The following nouns in -er are declined like puer: adulter, adulterer; gener, son-in-law; Līber, Bacchus; socer, father-in-law; vesper, evening; and compounds in -fer and -ger, as signifer, armiger.