first declension

In Latin, a pattern of inflection of a group of nouns that are declined (inflected) in the same way, and which have an -a- in their stems.

In Russian and Ukrainian, a pattern of inflection of a group of (mostly) feminine nouns that are declined (inflected) in the same way, and which end in -а/-я in the nominative singular.

In Lithuanian, a pattern of inflection of a group of masculine nouns that are declined (inflected) in the same way, and which end in -as/-is/-ys/-ias in the nominative singular; also a pattern of inflection of a group of adjectives that end in -(i)as in the masculine nominative singular.

In Latvian, a pattern of inflection of a group of masculine nouns that are declined (inflected) in the same way, and which end in -s/-š in the nominative singular, with thematic vowel -a-.

In Irish, a pattern of inflection of a group of masculine nouns that are declined (inflected) in the same way, and which end in a broad consonant in the nominative singular, and a slender consonant in the genitive singular; also a group of adjectives inflected similarly.

In Swedish, a pattern of inflection of a group of common-gender nouns that are declined (inflected) in the same way, and which end in -a or a consonant in the nominative singular, and -or in the nominative plural.