From Longman Dictionary of Contemporary Englishnutternut‧ter /ˈnʌtə $ -ər/ noun [countable] British English informal CRAZYa crazy person SYN idiot an absolute nutter
Examples from the Corpus
nutter• Burns can be a nutter - especially when he's had a few drinks.• That's got to be some kind of a nutter.• To call some one a nutter, however, is not to use what they would see as a term of abuse.• He was a nutter, Tony.• He's a complete nutter. He's got no sense whatsoever.• It could be useful when we get the usual clutch of nutters claiming they're the Whistler.• We are not cranks or nutters.• Let them figure out the connection between the nutter at the funeral and the man who was hanged all those years ago.• Sometimes you get these nutters calling you at 3 o'clock in the morning. 