1. verb To cause something to fall off of a surface by striking or colliding with it, either intentionally or unintentionally. In this usage, a noun or pronoun can be used between "knock" and "off." That's the third time this week that I've knocked a glass off the counter. Please don't dance so close to the table, you'll knock off those papers.

2. verb, slang To stop doing whatever one is doing. Often used as an imperative. In this usage, a noun or pronoun can be used between "knock" and "off," especially in the common phrase "knock it off." Knock it off, you two! I don't want to see any more fighting. I'm going to go tell those kids to knock off all the shouting.

3. verb, slang To copy or imitate a work or good, often without consent. Whoever knocked off that designer handbag did a good job—you can barely tell the difference. He's made a career out of knocking off the classics.

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

5. verb, slang To rob a physical location, such as a store, house, etc. The same guy has been knocking off convenience stores in the area, and police finally think they've identified him. You've got to be a fool to think you can knock off an ATM inside a police station.

6. verb, slang To take a break or stop working for the day. I'm going to knock off around six. You want to meet me for dinner?

7. verb, slang To murder someone. The mob has been knocking off every witness that has taken the stand, so now people are terrified to come forward.

8. verb, slang To reduce a price by a certain amount. Can you knock off a few bucks for an old friend?

9. verb, slang To defeat or eliminate from contention, as in a sports competition. Every year, some underdog knocks off a top-seeded team.

10. noun, slang A copy or imitation of a work or good, often produced without consent. In this usage, the phrase is usually hyphenated or spelled as one word. You can find all kinds of cheap knock-offs of designer goods being sold in the tourist district. A lot of critics love him, but I find him to be just another Hitchcock knock-off.