knock something on the head
knock (someone or something) on the head
1. Literally, to bump or strike someone on the head, either accidentally or intentionally. That book knocked me on the head when it fell off the shelf. Quit messing with me or I'll knock you on the head!
2. To promptly prevent something, especially an idea, suggestion, or plan, from being developed, proliferated, or carried out. Primarily heard in UK. We need to knock this notion of forming a union on the head before it gets too far. He's been trying to knock the rumours on the head, but by now nearly everyone has heard them.
3. To stop (doing) an activity or behavior. Primarily heard in UK. You need to knock that smoking on the head before the baby arrives. I briefly got into computer programming, but I knocked it on the head when things got more complicated.
knock something on the headBRITISH, INFORMAL
1. If you knock a story or idea on the head, you show that it is not true or correct. It's time to knock on the head the idea that we are not living a full life unless we have that special somebody in our lives. This is another fallacy that needs to be knocked on the head, the idea that women never went out to work till the First World War.
2. If you knock an activity on the head, you stop doing it, or decide not to do it. We'll never be like The Rolling Stones. When we stop enjoying ourselves, we'll knock it on the head.