baleen /bəˈliːn/ noun3 •keratinous material that makes up the plates in the mouth of the baleen whale (Mysticeti), which it uses to trap its food; formerly used in corsetry. •A baleen whale (Mysticeti).Scammon estimates the number of baleens killed in the years 1835-72 at 131,000; once again, his figure needs to be adjusted. — 2007 •(no longer used) Any whale or large fish.The Balene is a fishe great and huge, much like to the Whale, and is so called, because of his outcasting and shedding of water, for they throwe water higher then other great fishes of the sea. — 1572 formsbaleens