In grammar, pertaining to or indicating origin, source, possession, and the like: an epithet applied to a case in the declension of nouns, adjectives, pronouns, etc., which in English is called the possessive case, or to the relation expressed by such a case: as, patris, ‘of a father, a father's,’ is the genitive case of the Latin noun pater, a father.n. In grammar, a case in the declension of nouns, adjectives, pronouns, etc., expressing in the widest sense a relation of appurtenance between one thing and another, an adjectival relation of one noun to another, or more specifically source, origin, possession, and the like; in English grammar, the possessive case.n. Abbreviated genitiveConnected with or relating to generation.