To utter threats against; to menace; to inspire with apprehension; to alarm, or attempt to alarm, as with the promise of something evil or disagreeable; to warn.

To exhibit the appearance of (something evil or unpleasant) as approaching; to indicate as impending; to announce the conditional infliction of; as, to threaten war; to threaten death.

To use threats, or menaces; also, to have a threatening appearance.

pose a threat to; present a danger to; "The pollution is endangering the crops"

A THREAT is a move or plan which a player intends to carry out unless his opponent stops him. After 1. e2-e4 e7-e5 2. Qd1-h5, White ATTACKS e5, f7 and h7, but only Qh5xe5 is a THREAT: White THREATENS to take the e-pawn.