How is the declension of a noun determined?

The declension of a noun is determined primarily by its genitive singular form. This is because the genitive case often provides key information about the declension class to which the noun belongs. Each declension has characteristic endings in the genitive singular, which allows one to identify whether the noun follows the first, second, third, or another declension pattern.

For instance, in Latin, the genitive singular form of a first declension noun typically ends in "-ae," while a second declension noun commonly ends in "-i." By examining the genitive singular, you can accurately assign the noun to its proper declension pattern and predict its other forms, such as the nominative, accusative, and dative cases. This is essential for understanding how to decline the noun in various grammatical contexts and for constructing grammatically correct sentences.