A connoisseur or dedicated student of some activity; (subsequently esp.) an ardent follower of any sport, activity, or pastime; a fan. Frequently…

A person with an enthusiasm for and active interest in a particular form of sport or a particular team or club.

A fanatic; in modern English (originally U.S.): a keen and regular spectator of a (professional) sport, originally of baseball; a regular…

A fan or follower; (now) esp. an enthusiastic and committed supporter of a particular sport or team. Often in plural: such fans collectively.