Mandrill Man"drill, n. [Cf. F. mandrille, Sp. mandril, It. mandrillo; prob. the native name in Africa. Cf. Drill an ape.] (Zo["o]l.) a large West African baboon (Cynocephalus, or Papio, mormon). The adult male has, on the sides of the nose, large, naked, grooved swellings, conspicuously striped with blue and red.