Webster's Revised Unabridged Dictionary · 1913

(Zoology) A bird of the Parrot family, of the subfamily Cacatuina, having a short, strong, and much curved beak, and the head ornamented with a crest, which can be raised or depressed at will. There are several genera and many species; as the broad-crested cockatoo (Plictolophus cristatus or Cacatua cristatus), the sulphur-crested (Cacatua galerita or Plictolophus galeritus), etc. The palm cockatoo or great black cockatoo of Australia is Probosciger aterrimus (formerly Microglossus aterrimus).