A simultaneous check given by moving one piece to give check, thereby also unmasking another piece which also gives check.
A powerful type of discovered attack, which checks the King with two pieces. The King is forced to move and the enemy army is thus frozen for at least one tempo or move.
A check delivered by two pieces at the same time. A double check necessarily involves a discovered check.
DOCH: Double Check happens when it results of the last half-move of a chessplayer that two of his pieces simultaneously attack the opponent King. Generally there is in the same time a simple check (by one of both pieces) and a discovered check (by the other) (Chess Terminology).
check from two pieces at once, always obliging a King move. Examples in the Tactics section of the Canon.
In chess, a double check is a check delivered by two pieces at the same time.