Someone involved in a contest or battle (as in an agon), protagonist.
The muscle that contracts while the other relaxes.
A molecule that can combine with a receptor on a cell to produce a physiological reaction.
A participant; one involved in something.
An electronic device that plays audio and/or video media.
One who plays any game or sport.
A mechanism that actuates a player piano or other automatic musical instrument.
One who is playful; one without serious aims; an idler; a trifler.
A gambler.
A software application that plays audio and/or video media, such as a media player.
An actor in a dramatic play.
One who plays on a musical instrument.
A gamer; a player of video games or similar.
A person who plays the field rather than having a long-term sexual relationship.