He used a clever stratagem to deceive his opponent in the chess game.

stratagem 来自希腊语 strategema（军事计谋），由 stratos（军队）和 agein（带领）组成，指"精心设计的计策或战术"，常用于军事或竞争场合。这个词强调计谋的巧妙性和策略性。