Threatening to do two different attacks with one move. Often the opponent will only be able to defend against one of the attacks, or defend only partially against both.
Whenever possible, a player should make each move achieve at least two different goals or threats. Moves that contain only a single threat are generally not hard to meet. If a move contains multiple threats, the opponent may not be able to stop all the threats with a single move.
A Ladder Escape is a typical multiple threat.
It is sometimes called fork in hex and other games, and called miai in go.