Decoy
Luring a piece to a square where it becomes a target — usually by offering a sacrifice it cannot refuse.
A decoy attracts an enemy piece to a specific square where the next move exploits its new position. The standard pattern offers a sacrifice on the target square; the opponent must capture (or wishes to capture); the captured square becomes the launching point for a winning combination.
The classical decoy is the king decoy: a piece is sacrificed on a square near the enemy king, forcing the king to capture. The king on the new square is then mated or wins-of-material by a follow-up that would not have worked on the king’s previous square. The Greek Gift sacrifice — bishop takes h7 with check — is the most famous example, decoying the king to h7 (or h8) where a knight or queen follows up.
Decoys also work against non-royal pieces. A rook lured to a square where it is forked, a knight tempted to a square where it is trapped, a queen drawn to a square where it is exchanged off — all are decoys when the lure is what made the tactic work.
The line between decoy and deflection is sometimes blurry. Decoy implies that the piece arrives somewhere it was not before; deflection implies that the piece leaves somewhere it should have stayed. Both can be the same physical move described from different angles.