Latin has five basic groupings of nouns, which are called declensions. Because Latin is an inflected language, nouns consist of stems and endings. The endings specify the grammatical role that the noun plays in a sentence. The various declensions of Latin nouns are distinguished from one another by the ending used for the genitive (possessive) singular form of the noun. For example, all first-declension Latin nouns have a genitive singular ending of “-ae.” By contrast, second-declension Latin nouns have a genitive singular ending of “-i”.
In a Latin dictionary, an entry for a first-declension noun has three components. For example, consider the first-declension noun regina (queen). In a Latin dictionary, the word regina would be listed as follows:
regina, –ae, F.
The first component, regina, is the nominative singular form of the noun, which is used if regina is the singular subject of a sentence. The second component tells you the ending to be used for the genitive (possessive) singular form of the noun; the genitive singular of regina is reginae. (The ending -ae is added to the stem and elided with the letter “a” and the end of the nominative form.) The final component “F.” tells you that the noun’s gender is feminine. Most first-declension Latin nouns are feminine, with some exceptions.
Latin nouns have five cases, each of which may be singular or plural. The five cases are as follows:
Nominative (subject) Genitive (possessive) Dative (indirect object, to/for) Accusative (direct object) Ablative (from/with/in/by)
The following list shows the various endings for first-declension Latin nouns, using the word regina (queen) as an example:
Nominative singular: -a, regina (the/a queen)(subject) Genitive singular: -ae, reginae (of the queen)(possessive) Dative singular: -ae, reginae (to/for the queen)(indirect object) Accusative singular: -am, reginam (the/a queen)(direct object) Ablative singular: -a, regina (from/with/in/by the queen)
Plural:Nominative plural: -ae, reginae (the queens)(subject) Genitive plural: -arum, reginarum (of the queens, the queens’)(possessive) Dative plural: -is, reginis (to/for the queens)(indirect object) Accusative plural: -as, reginas (the queens)(direct object) Ablative plural: -is, reginis (from/with/in/by the queens)
To determine which ending and which form of a first-declension noun should be used, first determine the noun’s grammatical role in the sentence:If the noun is the subject of a sentence, use the nominative case and ending. (Example: The queen rules the kingdom.) If the noun is in the possessive case, use the genitive form. (Example: The kingdom is the queen’s) If the noun is an indirect object, use the dative case. (Example: The king gives the scepter to the queen.) If the noun is a direct object, use the accusative case. (Example: The king loves the queen.) If the noun follows a preposition, use the ablative case. (Example: The king rules with the queen.)