Definition of out to lunch in English:

out to lunch

phrase

informal
  • Temporarily not in command of one's mental faculties.

    • ‘I count the editor of the Independent as a friend, so the main reason I hesitate to say that he is out to lunch on this issue is that I was out to dinner with him last night.’
    • ‘I think unfortunately this doctor and her staff are a bit out to lunch… they seem unaware of what they are doing.’
    • ‘The waiters are a bit out to lunch and service was a bit slow, but we were not in a rush.’
    • ‘It's no use, because his support cast is either out to lunch, or not listening.’
    • ‘Of course, some people think I'm out to lunch because we don't do that in America.’
    • ‘He's out to lunch on this offshore thing but it's playing well at home.’
    • ‘Let us just say that, if not exactly out to lunch, she was certainly taking a coffee break and regrets her previous advice.’
    • ‘Many gay marriage opponents are just plain out to lunch.’
    • ‘The message was clear: parliament is out of touch as well as out to lunch.’