Nouns in the nominative and genitive
Creating noun forms is similar to creating finite verb forms: (1) you find the stem from the dictionary entry, and (2) add the proper ending. For finite verbs, you had to choose the appropriate principal part of the verb to find its stem. For nouns, you use the genitive singular form (the second word in a dictionary entry), and drop the genitive ending.
Endings for the nominative and genitive cases
First declension
Nouns using first declension endings can be masculine or feminine: you have to memorize the gender when you learn a vocabulary item.
Note that the genitive singular and the nominative plural of first-declension nouns have the same ending!
| Case | Singular | Plural |
|---|---|---|
| Nominative | -a | -ae |
| Genitive | -ae | -arum |
Example: femina, feminae f, “woman”
You can recognize from the genitive singular form that femina is a first-declension noun. Drop the -ae ending from the genitive singular to find the stem femin-, and add the appropriate endings for case and number.
| Case | Singular | Plural |
|---|---|---|
| Nominative | femina | feminae |
| Genitive | feminae | feminarum |
Second declension
Second declension nouns can be masculine or neuter. For masculine nouns of the second declension, the genitive singular and the nominative plural of first-declension nouns have the same ending – the same ambiguity as the first declension!
| Case | Singular | Plural |
|---|---|---|
| Nominative | -us or -er | -i |
| Genitive | -i | -orum |
Compare the forms for these two masculine nouns:
- filius, filii m: “son”
- liber, liberi m: “child”
You can see from the first form that filius has an ending in -us. Note that when we drop the -i from the genitive singular, the stem is fili-.
| Case | Singular | Plural |
|---|---|---|
| Nominative | filius | filii |
| Genitive | filii | filiorum |
liber has no ending added to its stem in the nominative singular: the nominative singular form is identical to the stem we find from dropping the genitive singular ending.
| Case | Singular | Plural |
|---|---|---|
| Nominative | liber | liberi |
| Genitive | liberi | liberorum |
Neuter nouns differ from masculine nouns of the second declension in the nominative case. You can always distinguish the nominative and genitive of neuter nouns.
| Case | Singular | Plural |
|---|---|---|
| Nominative | -um | -a |
| Genitive | -i | -orum |
oppidum, oppidi n: “town”
| Case | Singular | Plural |
|---|---|---|
| Nominative | oppidum | oppida |
| Genitive | oppidi | oppidorum |
Third declension
Third declension nouns can be masculine, feminine or neuter. The form of the nominative singular can look quite different from the genitive singular, but to create all the other forms, you follow the regular process of adding the correct endings to the stem you find from the genitive singular (for the third declension, by dropping -is).
Note that the genitive plural ending resembles the nominative singular ending of second declension neuter nouns like oppidum!
Masculine and feminine nouns normally use this set of endings:
| Case | Singular | Plural |
|---|---|---|
| Nominative | (varies) | -es |
| Genitive | -is | -um |
canis, canis m or f: “dog”
| Case | Singular | Plural |
|---|---|---|
| Nominative | canis | canes |
| Genitive | canis | canum |
A few third declension nouns called “i-stems” have a genitive plural in -ium.
auis, auis f: “bird”
| Case | Singular | Plural |
|---|---|---|
| Nominative | auis | aues |
| Genitive | auis | auium |
Neuter nouns have the same nominative plural ending as second-declension neuters.
caput, capitis n: “head”
| Case | Singular | Plural |
|---|---|---|
| Nominative | caput | caputa |
| Genitive | caputis | caputum |
Neuter i-stems show the -i- in the nominative plural as well as the genitive plural.
mare, maris n: “sea”
| Case | Singular | Plural |
|---|---|---|
| Nominative | mare | maria |
| Genitive | maris | marium |