Gnu \Gnu\, n. [Hottentot gnu, or nju: cf. F. gnou.] (Zo["o]l.) One of two species of large South African antelopes of the genus {Catoblephas}, having a mane and bushy tail, and curved horns in both sexes. [Written also {gnoo}.] Note: The common gnu or wildebeest ({Catoblephas gnu}) is plain brown; the brindled gnu or blue wildebeest ({C. gorgon}) is larger, with transverse stripes of black on the neck and shoulders.