訓 ひじ ・ 音 チュウ
Sino-Vietnamese: trửu
The body radical 月 plus 寸 (a hand measure): the joint of the arm above the hand, the elbow.
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
机に肘をつくのは失礼だ。 (つくえにひじをつくのはしつれいだ)
Resting your elbows on the desk is rude.