In informal British English, a nutter is a person other people think is crazy — someone who does wild, strange, or dangerously silly things. It is slang, and it is not kind.

In informal British English在英式非正式英文裡，a nutter is a person other people think is crazynutter指的是被別人覺得很瘋的人——someone who does wild, strange, or dangerously silly things一個會做出瘋狂、怪異，或危險傻事的人。It is slang, and it is not kind這是俚語，而且不太友善。

You would not say it to someone’s face unless you were joking with a very close friend, and even then it can hurt.

You would not say it to someone's face你通常不會當面對人這樣說，unless you were joking with a very close friend除非是跟很熟的朋友開玩笑，and even then it can hurt即使如此也可能傷人。

It is not a doctor’s word; it is just a rough way of saying “this person seems mad to me.” Though actually, people sometimes use it half-fondly, as in “He’s a bit of a nutter, but he’s harmless.” American speakers are more likely to say nut, nutcase, or crazy.

It is not a doctor's word這不是醫生用的字眼；it is just a rough way of saying "this person seems mad to me."只是一種粗略的說法，表示「這個人在我看來有點瘋」。Though actually, people sometimes use it half-fondly不過其實，有時候大家會帶點寵溺地這樣說, as in "He's a bit of a nutter, but he's harmless."像是「He's a bit of a nutter, but he's harmless.」American speakers are more likely to say nut, nutcase, or crazy美國人比較常說nut、nutcase，或直接說crazy。

Do not use it in class, in a job, or about someone who is really unwell.

Do not use it in class, in a job, or about someone who is really unwell不要在課堂上、工作場合，或用在真的生病的人身上使用這個字。