The term for a special relationship between the positions of the kings, partly depending on the distance between them.

The diagram shows the kings in direct (as opposed to distant) opposition. Both pieces have advanced to prevent the other gaining ground, but the position shows it is a disadvantage to have the next move (and it is thus also a zugzwang). White to move gives Black "the power of the opposition" (to block or advance further) or, put simply, "the opposition".