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When a Piece or Pawn is in a situation to be taken by the enemy, it is said to be en prise. To put a piece en prise, is to play it so that it may be captured.

Howard Staunton (1847). “The chess-player's handbook ...: with frontispiece”, p.21
When a Piece or Pawn is in a situation to be taken by the enemy, it is said to be en prise. To put a piece en prise, is to play it so that it may be captured.