Pygarg \Py"garg\, Pygargus \Py*gar"gus\, [L. pygargus, Gr. ?, literally, white rump; ? the rump + white: cf. F. pygargue.] 1. (Zo["o]l.) A quadruped, probably the addax, an antelope having a white rump. --Deut. xiv. 5. 2. (Zo["o]l.) (a) The female of the hen harrier. (b) The sea eagle.