stag

An adult male deer, especially a red deer and especially one in high adulthood versus a young adult.

The city recently carried out a deer census, determining there are 313 stags (males), 798 does (females) and 214 fawns (babies) in Nara Park.

A young horse (colt or filly).

A male turkey: a turkeycock.

A romping girl; a tomboy.

An improperly or late castrated bull or ram – also called a bull seg (see note under ox).

To act as a "stag", an irregular dealer in stocks.

To watch; to dog, or keep track of.

Of a man, attending a formal social function without a date.

My brother went stag to prom because he couldn't find a date.