Wearing no clothes at all — naked. This is British slang and it is casual and light-hearted; it makes the situation sound funny rather than shocking or sexual. You would use it about someone running out of the bathroom, or a child who pulled off their clothes, or a friend in an embarrassing story. It is an adjective that comes after the verb: he was starkers, she ran outside starkers. You do not put it before a noun — nobody says 'a starkers man'. Americans generally do not use it and may not know it. In writing it belongs only in relaxed, chatty places. There is also an older, rarer British use meaning 'completely mad', from stark raving mad, but the naked meaning is the one you will meet.

（英式俚語）光溜溜、全裸，語氣是好笑的那種，不是色情的。中文口語像「脫光光」。正式場合講 naked 就好，starkers 是英國人閒聊在用的。