膝ひざをつく

expression, godan verb (-ku)

fall to one's knees; go down on one's knees

Describes the action of dropping to one's knees, often from exhaustion, shock, or as a gesture of supplication or deep respect.

• 彼かれは疲つかれ果はてて、その場ばに膝ひざをついた。

  Exhausted, he fell to his knees on the spot.

• 謝しゃ罪ざいの気き持もちを表あらわすために、彼かれは床ゆかに膝ひざをついた。

  To express his apology, he went down on his knees on the floor.