1. verb To cause something to fall out of something else by striking or colliding with it, either intentionally or unintentionally. In this usage, a noun or pronoun can be used between "knock" and "out." I tried to knock out the broken piece, but it seems like it's stuck in there. When Dave crashed his bike, he knocked the mail out of the mailbox. It was actually kind of funny.

2. verb To render one unconscious, as from a physical blow or a drug. In this usage, a noun or pronoun can be used between "knock" and "out." You really think you can knock out the champ? We're going to knock you out for this procedure, so you won't feel any pain at all.

3. verb To exhaust one or make one fatigued. In this usage, a noun or pronoun is used between "knock" and "out." It's amazing how standing all day can really knock you out. My medication usually knocks me out, so I better stay home for the day.

4. verb, slang To thoroughly impress, overwhelm, or excite one. In this usage, a noun or pronoun is used between "knock" and "out." The show of support from everyone just knocked me out. That movie really knocked me out—I didn't expect it to be so good!

5. verb, slang To cause to stop operating or functioning. In this usage, a noun or pronoun can be used between "knock" and "out." The storm knocked out power to the whole island. Be careful not to overload the system—you could knock it out with too much traffic.

6. verb, slang To eliminate from contention, as in a sports competition. In this usage, a noun or pronoun can be used between "knock" and "out." Every year, some underdog knocks out a top-seeded team. I'd love to knock the defending champs out of the tourney, but it will take a miracle.

7. verb, slang To produce or complete something, usually with the main motivation of simply getting it done. If we can knock out a few more of these reports before the weekend, we'll be in good shape for next week. I'm just trying to knock out as many pages as possible so I can get up to the page count before the deadline.

8. noun In boxing and similar sports, a blow that renders one unconscious or technically disqualifies one from continuing, or the result of a match in which such a blow has occurred. In this usage, the phrase is usually hyphenated or spelled as one word. That was a vicious knockout by the newcomer. His record is 10-0, with eight knockouts.

9. noun An elimination from contention, as in a sports competition. In this usage, the phrase is usually hyphenated or spelled as one word. I can't believe there were six knockouts in the first round!

10. noun, slang A great success. In this usage, the phrase is usually spelled as one word. I think this release is going to be a real knockout. Great job, everyone!

11. noun, slang A beautiful person, typically a woman. In this usage, the phrase is usually spelled as one word. Remember Paula from high school? Well, she's a knockout know, and she's dating Mike Miller!