The second declension consists of Latin nouns with stems ending in ·o. Second declension nouns have nominative singular forms ending in ·us, ·er or ·um.
·us words
Most second declension nouns have a nominative singular form ending in ·us. These nouns are usually masculine:
| singular | plural | |
|---|---|---|
| nominative | amicus | amici |
| vocative | amice | amici |
| accusative | amicum | amicos |
| genitive | amici | amicorum |
| dative | amico | amicis |
| ablative | amico | amicis |
Exceptions
·ius nouns
Nouns with a nominative singular form ending in ·ius decline slightly differently: their vocative singular form ends in ·i.
| singular | plural | |
|---|---|---|
| nominative | filius | filii |
| vocative | fili | filii |
| accusative | filium | filios |
| genitive | filii / fili | filiorum |
| dative | filio | filiis |
| ablative | filio | filiis |
deus -i m., god
deus -i m., god has some irregular plural forms:
| singular | plural | |
|---|---|---|
| nominative | deus | di |
| vocative | — | di |
| accusative | deum | deos |
| genitive | dei | deorum / deum |
| dative | deo | dis |
| ablative | deo | dis |
·er words
Some second declension words have a nominative singular ending in ·er. These words are all masculine. Some of these words drop the ·e· when they add an ending:
| singular | plural | |
|---|---|---|
| nominative | ager | agri |
| vocative | ager | agri |
| accusative | agrum | agros |
| genitive | agri | agrorum |
| dative | agro | agris |
| ablative | agro | agris |
Others keep the ·e· when they add an ending:
| singular | plural | |
|---|---|---|
| nominative | puer | pueri |
| vocative | puer | pueri |
| accusative | puerum | pueros |
| genitive | pueri | puerorum |
| dative | puero | pueris |
| ablative | puero | pueris |
You need to learn which words drop the ·e· and which ones keep it.
| drops the ·e· | keeps the ·e· | no ·e· |
|---|---|---|
| ager agri m., field, land | puer pueri m., boy | vir viri m., man |
·um words
Second declension words with a nominative singular ending in ·um are all neuter. As a result, their nominative, vocative and accusative singular forms are all the same, and their nominative, vocative and accusative plural forms all end in ·a.
| singular | plural | |
|---|---|---|
| nominative | saxum | saxa |
| vocative | saxum | saxa |
| accusative | saxum | saxa |
| genitive | saxi | saxorum |
| dative | saxo | saxis |
| ablative | saxo | saxis |