Despite feeling disappointed, he dissembled his emotions and politely congratulated his opponent.

dissembled 是动词 dissemble 的过去式。dissemble 由前缀 dis-（表示"否定、相反"）和词根 semble（来自拉丁语 simulare，意为"假装、模仿"）组成，字面意思是"不真实表现"，即"掩饰、隐藏（真实情感或意图）"。