1. slang Eccentric or completely or wildly deviating from the norm. My uncle has always been a little bit screwy, never really fitting in with the rest of us. We don't need another one of your screwy ideas, Tom.

2. slang Not functioning correctly or as expected. This computer is acting screwy lately. Could you have a look at it and see what the problem is? The washing machine has been really screwy ever since Tom tried repairing the pump himself.

3. slang Having an altered or less coherent state of mind. I tried going on medication to help ease the symptoms, but it always left me feeling screwy. You always get a bit screwy when you smoke that stuff!