In grammar, an epithet given to a case in the declension of nouns, expressing primarily the thing from which something else proceeds; as filius patris, the son of a father; aqua fontis, the water of a fountain. But by custom this case expresses other relations, particularly possession or ownership; as animi magnitudo, greatness of mind, greatness possessed by or inherent in the mind. This case often expresses also that which proceeds from something else; as pater septem filiorum, the father of seven sons.

Of or pertaining to that case (as the second case of Latin and Greek nouns) which expresses source or possession. It corresponds to the possessive case in English.

The genitive case.