1To peel or pare — a transitive verb meaning to remove a skin, shell, or outer layer (e.g., of fruit or vegetables).
リンゴの皮を包丁でむく。
I peel an apple with a knife.
魚を料理する前にウロコをむいておく。
Before cooking the fish, I scale (remove the scales from) it.
エダマメの殻をむいて塩を振る。
I shell the edamame and sprinkle salt.
2To bare (teeth) or to open wide (one's eyes) — used in expressions like 'to bare one's fangs' or 'to open one's eyes wide' (transitive).
犬が警戒して牙をむいた。
The dog bared its teeth in warning.
その知らせを聞いて彼女は目をむいた。
She opened her eyes wide when she heard the news.