LUNATIC

[adjective]That's a lunatic (= extremely foolish and careless) way to behave.(disapproving or humorous) It's no longer just people on the lunatic fringe (= people who have very strong opinions which are outside the usual range) who are concerned about the growing use of nuclear power.(dated, now taboo) A lunatic asylum is a hospital for mentally ill people.There are no longer any lunatic asylums in the UK.