Mangabey \Man"ga*bey\, n. [So called by Buffon from Mangaby, in Madagascar, where he erroneously supposed them be native.] (Zool.) Any one of several African monkeys of the genus {Cercocebus}, as the sooty mangabey ({Cercocebus fuliginosus}), which is sooty black. [Also written {mangaby}.] [1913 Webster]