knock: [OE] knock is a classic onomatopoeic word: that is to say, it originated in a direct imitation of the sound it denotes. The similar Swedish knacka ‘knock’ may be related. The figurative use of the word for ‘criticize’ originated in late 19th-century America.
knock (v.)
Old English cnocian (West Saxon cnucian), "to pound, beat; knock (on a door)," likely of imitative origin. Meaning "deprecate, put down" is from 1892. Related: Knocked; knocking. Knock-kneed first attested 1774. Knock-down, drag-out is from 1827. Command knock it off "stop it" is first recorded 1880, perhaps from auctioneer's term for "dispose of quickly:"
At the commencement of the sales, he gave every one that wanted to purchase a paper containing a description of the lands that were to be sold; and, as the sales were cried, he called over the numbers and described the land; and when it got up to one dollar and a quarter an acre, if no body bid, after it was cried two or three times, he would say, knock it off, knock it off. [U.S. Senate record, 1834]
knock (n.)
mid-14c., from knock (v.). As an engine noise, from 1899.
中文解释
谐音助记：脑壳。敲脑壳。
实用例句
1. Find Bernie and get him to knock an agreement together.
找到伯尼，让他尽快拟好一份协议。来自柯林斯例句
2. They decided to knock the two rooms into one.
他们决定把两间屋子打通连成一间。来自柯林斯例句
3. What they said was a real knock to my self-confidence.
他们的话是对我自信心的一次重大打击。来自柯林斯例句
4. He had many motives for wanting to knock off Yvonne.
他有很多杀伊冯娜的动机。来自柯林斯例句
5. When we stop enjoying ourselves we'll knock it on the head.
