a. [ L. hydragogus conveying off water, Gr. &unr_;; "y`dwr water + &unr_; to lead: cf. F. hydragogue.] (Med.) Causing a discharge of water; expelling serum effused into any part of the body, as in dropsy. -- n. A hydragogue medicine, usually a cathartic or diuretic. [1913 Webster]