Cosinage \Cos"in*age\ (k?s"'n-?j), n. [See {Cousinage}.] (Law) (a) Collateral relationship or kindred by blood; consanguinity. --Burrill. (b) A writ to recover possession of an estate in lands, when a stranger has entered, after the death of the grandfather's grandfather, or other distant collateral relation. --Blackstone.