(1):

(a.) Of the same or a similar nature; of the same family; proceeding from the same stock or root; allied; kindred; as, a cognate language.

(2):

(n.) One who is related to another on the female side.

(3):

(n.) One of a number of things allied in origin or nature; as, certain letters are cognates.

(4):

(a.) Allied by blood; kindred by birth; specifically (Law), related on the mother's side.