In the chess match, he defeated his opponent in just three moves.

defeated 是动词 defeat 的过去式形式。defeat 由前缀 de-（表示"去除、剥夺"）和词根 feat（古法语词，意为"功绩、成就"）组成，字面意思是"使对方的功绩失效"，引申为"击败、战胜"的意思。