a large, dark-gray, earless seal (Cystophora cristata) of the N Atlantic: the male has on its head a hoodlike sac that can be inflated
See hooded seal in American Heritage Dictionary 4
noun
A seal (Cystophora cristata) of northern seas, having a grayish, spotted coat and an inflatable hoodlike or bladderlike pouch in the region of the nose. Also called bladdernose.