1st & 2nd Declension Adjectives (-us, -a, -um)
Adjectives in Latin must match the noun they modify in gender, number, and case. The most common adjectives use 1st and 2nd declension endings.
Masculine (2nd Decl)
Masculine Endings
| Case | Singular | Plural |
|---|---|---|
| NOMNominative | -us | -ī |
| GENGenitive | -ī | -ōrum |
| DATDative | -ō | -īs |
| ACCAccusative | -um | -ōs |
| ABLAblative | -ō | -īs |
| VOCVocative | -e | -ī |
Example: magnus, -ī
Feminine (1st Decl)
Feminine Endings
| Case | Singular | Plural |
|---|---|---|
| NOMNominative | -a | -ae |
| GENGenitive | -ae | -ārum |
| DATDative | -ae | -īs |
| ACCAccusative | -am | -ās |
| ABLAblative | -ā | -īs |
| VOCVocative | -a | -ae |
Example: magna, -ae
Neuter (2nd Decl)
Neuter Endings
| Case | Singular | Plural |
|---|---|---|
| NOMNominative | -um | -a |
| GENGenitive | -ī | -ōrum |
| DATDative | -ō | -īs |
| ACCAccusative | -um | -a |
| ABLAblative | -ō | -īs |
| VOCVocative | -um | -a |
Example: magnum, -ī
Adjective Agreement Rules
1. Gender: If the noun is masculine, use the masculine form. If it's feminine, use the feminine form.
2. Number: If the noun is plural, the adjective must also be plural.
3. Case: If the noun is the direct object (accusative), the adjective must also be accusative.
Example in Practice
puella magnaGreat girl (Nom Sg F)
nauta magnusGreat sailor (Nom Sg M)
pecūniam multamMuch money (Acc Sg F)
Notice that nauta is masculine even though it ends in -a, so it takes the masculine magnus!