1.a man or boy who is enthusiastic about and good at sport
He didn't want to be thought of just as a dumb jock who played football.
In high school, either you were a games geek or a sports jock.
2.short for jockstrap : a tight piece of underwear worn by men to support and protect their sexual organs when playing sport
He was sitting in the corner of the locker room wearing only his jock.
3.a piece of underwear worn by men and boys that covers the area between the waist and the tops of the legs
He was only wearing a pair of jocks.
4.a man who comes from Scotland. This word is considered offensive by some people.
5.a person, esp. a young man, who is extremely enthusiastic about and good at sports
Everyone on campus thought I was just another dumb jock.