The phrasal a verb 'knock out' has several meanings. To knock out a person means to render them unconscious with the use of drugs or physical violence. In boxing, a knock out signals the end of a boxing match when one competitor cannot get up within a specific time. As an adjective, someone who is described as a knock out is someone who is extremely physically attractive or appealing. In science, knock out can refer to a gene which is removed or inactivated with genetic engineering. If you produce something quickly or roughly, you can use knock out for example, 'we knocked out a prototype quickly over the weekend'. Knock out can also mean to make something useless or unable to work. To knock out can also mean to eliminate or remove something or someone such as getting knocked out of the game. If you say you are knocked out it can also mean you feel extremely tired or exhausted.

1. While I waited for my package to arrive, I decided to knock out a few of my household chores.
2. The tablets make me feel extremely tired and hour after taking them I am completely knocked out.
3. It didn't take me long to make the cakes I knocked them out while I was making dinner.

1. I've knocked out a first draft of the proposal, just so we have something to show to the investors tomorrow. We can work on it in more detail at a later date.
2. At the moment, Robert is frantically knocking out the reports on his to-do list so that he can have the weekend off.