cognate

One of a number of things allied in origin or nature.

(law, dated) One who is related to another on the female side.

(law, dated) One who is related to another, both having descended from a common ancestor through legal marriages.

(linguistics) A word either descended from the same base word of the same ancestor language as the given word, or strongly believed to be a regular reflex of the same reconstructed root of proto-language as the given word.