v (1)敲，击，打(strike a sounding blow，as in seeking admittance，calling attention，or giving a signal;hit;strike)[I，I+prep，T+n，T+n+prep]：Please～before entering. 进来前请敲门。～at (on) the door/the window 敲门/窗;～on wood for luck 击木求好运;～sb's head 敲某人的头;～sb on the head 打某人的头;～a cup off the table 碰掉桌上的杯子;～one's knee against the chair 自己的膝盖撞在椅子上;～oneself on the corner of the table 自己碰到桌角上;～some nails into the wall 把钉子钉在墙上;〖同〗strike，hit，tap，bang;

(2)把……击(撞)使成某种状态;打(敲)成……((cause to)be in a certain state or position by hitting;drive，force or render by striking)[C+n+adj，C+n+ing，T+n+prep]：～sb senseless/unconscious/flat with one punch 一拳把某人击昏/击得失去知觉/击倒;～sb's drink flying 把某人的酒碰翻;～a hole in the wall/the fence/the door 在墙/篱笆/门上打个洞;～sb sideways(infml)击败;使目瞪口呆;〖同〗 hit，strike，slam，pound;

(3)找碴儿，挑剔(find fault with or criticize，etc unfairly)[T+n](infml)：be too fond of～ing others 太爱找别人的碴儿;～sb's work/sb's latest play/one's country's foreign policy 挑剔别人工作/他人最新剧本/自己国家外交政策的毛病;〖同〗criticize，abuse，condemn;

(4)(发动机等)因故障而发出爆震或砰砰声((of an engine) make a noise because sth is wrong)[I]：The engine of our car is～ing badly.我们汽车的发动机发出很大的爆震声响。

knock spots off (infml) 远远胜过： Tom can～spots off me at tennis. 汤姆打网球比我好得多。

knock the bottom out of sth 破坏，使失败：The new law～ed the bottom out of his investment almost overnight. 这条新法律几乎一夜之间使他的投资荡然无存。

knock the stuffing out of sb (infml) 使懊丧(士气低落)： Jennie's failure in the exam has～ed all the stuffing out of her. 考试不及格使珍妮懊丧不已。

you could have knocked me down with a feather (infml) 我大为吃惊： We all thought that my uncle was dead，so when he walked into the room you could have～ed me down with a feather!我们都认为我叔叔死了，所以当他走进屋时，我简直惊呆了!

knock about (v adv/prep)(infml) 1)漫游，流浪(vi)：Our elder son has been～ing about(on) the Continent for several months. 我们的大儿子已经游历欧洲大陆数月之久。2)殴打;粗暴地对待(vt)：If that man～s his wife about any more he'll be sent to prison. 如果那男子再虐待他妻子，他将被送进监狱。

knock back (v adv)(infml) 1)痛饮(vt)：～back a pint of beer 迅速饮了一品脱啤酒;2)花费(钱)(vt 无pass)：How much did that new watch～you back? 那只新表花了你多少钱? 3)使吃惊(vt)：The news～ed him back. 这消息使他大吃一惊。

knock down (v adv) 1)拆掉(vt 常 pass)：These old houses are to be～ed down. 这些旧房子将被拆除掉。2)撞倒(vt 常pass)：He was nearly～ed down by a taxi.他差一点被一辆出租车撞倒。3)使减价，把(价钱)压低(vt 常pass)：He～ed down the price by ten per cent. 他把价格压低了10%。4)(以低价)拍卖掉 (vt 常pass)： A mahogany table was～ed down for five pounds. 桃花心木的桌子以五英镑的低价被拍卖掉。

knock off (v adv) 1)减价，扣掉(vt)：They～ed five pounds off the price. 他们把价格降低了五英镑。2)停止(工作)(infml)(vt & vi)：My health compels me to～off (work). 我的健康状况迫使我停止工作。3)迅速完成(infml)(vt)：The boy～ed off his homework in half an hour. 那小男孩半小时之内匆忙完成了作业。4)盗，抢;杀(sl)(vt)：Who's～ed off my coat? 谁偷了我的上衣? They～ed off a bank. 他们抢了一家银行。

knock out (v adv) 1)(拳击中)击败对手(vt)：The boxer～ed out his opponent in the second round. 该拳击手在第二轮中把对手击败。2)使失去知觉，使昏迷(infml)(vt)：A blow on the head～ed him out. 头上挨的一击使他昏迷不醒。3)使震惊(infml)(vt)：She was～ed out by the news. 她被那消息惊得目瞪口呆。4)摧毁(vt)：The soldier～ed out two enemy tanks with his bazooka. 那战士用反坦克火箭筒击毁了敌军两辆坦克。5)磕净烟斗(vt)：K～out your pipe and then refill it. 磕净烟斗，再装一袋。6)淘汰(vt)：Our team were～ed out of the competition in the second game. 第二局我们队被淘汰。

knock over (v adv) 打翻(vt)：Who～ed that bottle over? 谁打翻了那瓶子?

knock together(v adv)粗糙地制作(vt)： They～ed together a rough box with wooden boards. 他们用木板草草地做成一个粗糙的箱子。

knock up (v adv) 1)敲门叫醒(BrE)(infml)(vt)：Tell him to～me up at six o'clock. 告诉他6点钟叫醒我。2)仓促建造(vt)：We～ed up a hut for the mountain climbers. 我们为登山运动员匆匆搭起了一个小屋。3)使怀孕(AmE)(sl)(vt)：If you～your girlfriend up you'll be in trouble with her family. 如果你使你的女朋友怀孕，你会和她家有麻烦的。4)(网球，羽毛球等)赛前练习(vi)：The players are allowed to～up for three minutes before starting the game. 比赛前允许运动员练习三分钟。

→′knockabout adj 喧(吵)闹的;′knock-down adj 能拆卸的;廉价的;′knocker n 敲击者(物);门环;吹毛求疵的人;knock-′kneed adj 膝内翻的;knock-′on n(橄榄球)要接球时用手将球击向前方的犯规动作;knock-′on effect n 间接的负面影响;′knock-out n 击倒;淘汰赛;异常动人的人;强麻醉药;′knock-up n 赛前的准备活动;

n (1)敲(叩)击;敲击(门)声(act or sound of knocking)[C]：get a nasty～on the head 头撞得很厉害;hear a～at the door 听到敲门声;hard～s激烈的碰撞;〖同〗stroke，hit，bang，tap，pat，crash，crack;

(2)挫折，不愉快的事(unfortunate experience)(infml)[C]：have a few/suffer some hard～s 遭受不少挫折;take a～(infml)遭受金钱或精神打击;

(3)(发动机等的)震动声(noise resulting from incorrect functioning of some part of an engine)[C];

【辨异】knock与bang和bump的区别见BANG。