An endgame term meaning the king not forced to move. Where the two kings stand on the same file or diagonal with an odd number of squares between them, the player that doesn't have to move is said to "have the opposition." This is important in king and pawn endings as the player who can secure the opposition can effectively guard certain spaces or drive the opposing king back.

A position in which two kings stand on the same rank, file or diagonal with one empty square between them. The player to move may be forced to move the king to a less advantageous square. Opposition is a particularly important concept in endgames. One orthogonal square separation is direct opposition; one diagonal square is diagonal opposition; multiple squares separation is distant opposition. Cf. corresponding squares.