n. [ F. cachalot. ] (Zoöl.) The sperm whale (Physeter macrocephalus). It has in the top of its head a large cavity, containing an oily fluid, which, after death, concretes into a whitish crystalline substance called spermaceti. See Sperm whale. [ 1913 Webster ]
(n) large whale with a large cavity in the head containing spermaceti and oil; also a source of ambergris, Syn. cachalot, black whale, Physeter catodon