noun
Archaic noun describing a facial expression of triumph or self-satisfaction. Modern Japanese would more commonly use 得意顔 or ドヤ顔.
See also: 得意顔
彼は得たり顔で部屋に入ってきた。
He entered the room with a triumphant look on his face.
Compound of 得たり (etari, 'got it!' or 'I've done it!') and 顔 (kao, 'face'). The exact historical derivation is uncertain, but it likely originated as a set phrase describing the expression of someone who has achieved something.