膝ㄒㄧxī袒ㄊㄢˇtǎn

袒露上身，跪地以膝蓋前進。《資治通鑑·卷一四四·齊紀十·和帝中興元年》：「自承麾旆屆止，莫不膝袒軍門。」

英to walk on one's knees and bare one's breast (a gesture of deepest apology)