I heard people said "half stupid" in Ghostbusters Film 2016. I am not sure if I misheard it. But:
half (adv): partly
The chicken was only half cooked.
So, "he is half stupid" = "he is partly stupid"? is it right?
is "half stupid" idiomatic? or
is it common to say like that?
This is an idiomatic saying. You are correct in thinking that it means partly stupid. Usually it is used not as a judgement on intelligence, and more to comment that a person is half stupid, and half smart, or that they do stupid things or act in a stupid way some of the time, rather than they lack intelligence.
