To strike one with great force, usually in the head. Usually used as a threat or a hypothetical action. If you insult me like that again, I'll knock your head off!That football nearly knocked my head off. I'm glad I ducked in time!See also: head, knock, off
I’ll knock your ˈblock/ˈhead off!
(British English, spoken) used to threaten somebody that you will hit themSee also: block, head, knock