Definition of platoon player in US English:

platoon player

noun

North American
Sport
  • 1Amer. Football. A player in a unit of attack or defence; specifically a player who plays in only one such unit.

  • 2Baseball. A player who alternates with another player in a fielding position. Also (more generally): a player who specializes in one skill, batting style, etc. and is most often substituted into a game as such (especially when batting).

Origin

1950s; earliest use found in The Los Angeles Times. From platoon + player.

Pronunciation

platoon player

/pləˈtuːn ˌpleɪə/