1. 使不省人事；使入睡
To knock someone out means to cause them to become unconscious or to go to sleep.

2. 击败；淘汰
If a person or team is knocked out of a competition, they are defeated in a game, so that they take no more part in the competition.

3. 摧毁；使瘫痪
If something is knocked out by enemy action or bad weather, it is destroyed or stops functioning because of it.

1. destroy or break forcefully

e.g. The windows were knocked out

2. empty (as of tobacco) by knocking out

e.g. knocked out a pipe

3. eliminate

e.g. knock out a target

4. knock unconscious or senseless

e.g. the boxing champion knocked out his opponent in a few seconds

Synonym: knock coldkayo

5. overwhelm with admiration

e.g. All the guys were knocked out by her charm