the adult male of the red deer (cervus elaphus), a large european species closely related to the american elk, or wapiti.-the male of certain other species of large deer.-a colt, or filly; also, a romping girl.-a castrated bull; -- called also bull stag, and bull seg. see the note under ox.-an outside irregular dealer in stocks, who is not a member of the exchange.-one who applies for the allotment of shares in new projects, with a view to sell immediately at a premium, and not to hold the stock.-the european wren.-to act as a "stag", or irregular dealer in stocks.-to watch; to dog, or keep track of.