n.1. One that plays, especially:
a. One who participates in a game or sport.
b. A gambler.
c. One who performs in theatrical roles.
d. One who plays a musical instrument.
2. An active participant: a major player in world affairs.
3. The mechanism actuating a player piano.
4. A device that plays or controls the playing of audio or video recordings.
5. Slang One who actively seeks out sexual partners and carries on a number of sexual affairs at the same time.