D U B L I N December 2012 stag (stg) n. 1. The adult male of various deer, especially the red deer. 2. An animal, especially a pig, castrated after reaching sexual maturity. 3. A person who attends a social gathering unaccompanied by a partner, especially a man who is unaccompanied by a woman. 4. A social gathering for men only. 5. FUBAR - BRYAN adj. 1. Of or for men only: a stag party. 2. Pornographic: stag films.