- Informal. an alcoholic drink taken at bedtime or at the end of a festive evening.
- a cap for the head, intended primarily to be worn in bed.
- Sports Informal. the last event of the program for the day, especially the second game of a doubleheader in baseball or the last race of the day in horse racing.
- a bedtime drink, esp an alcoholic or hot one
- a soft cap formerly worn in bed
also night-cap, late 14c., “covering for the head, worn in bed,” from night + cap (n.). In the alcoholic sense, it is attested from 1818. American English sense of “final event in a sporting contest” (especially the second game of a baseball double-header) is from 1939.