once

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++once1 /wʌns/ ●●● S1 W1 adverb  1  ONCEon one occasion only 一次，一回 I’ve only met her once. 我只见过她一面。 Paul’s been to Wexford once before. 保罗曾去过韦克斯福德一次。(just) the once British English spoken Mrs Peterson came in to see Ruth just the once. 彼德森太太仅仅来看过露丝一次。2  once a week/once every three months etc REGULARone time every week etc, as a regular activity or event 每周一次/每三个月一次等 Staff meetings take place once a week. 员工会议每周举行一次。 They took separate holidays at least once every two years. 他们每两年至少有一次各自去度假。3  PASTat some time in the past, but not now 曾经，以前 Sonya and Ida had once been close friends. 索尼娅和艾达曾经是很要好的朋友。 She and her husband had once owned a house like this. 她和她丈夫曾经也有过这样的房子。once-great/proud etc It was sad to see the once-great man looking so frail. 看到曾经的伟人如此脆弱，真让人难过。 the once-mighty steel industry 一度辉煌的钢铁工业4  in the past, at a time that is not stated 过去，曾经 I once ran 21 miles. 我曾经跑过21英里。 Marx once described religion as the ‘opium of the people’. 马克思曾把宗教称为“人民的鸦片”。5  at once a) IMMEDIATELYimmediately or without delay 立刻，马上 Now, go upstairs at once and clean your room! 现在立刻上楼去打扫你的房间！ When I saw him I recognized him at once. 一看到他我就认出他了。 b) TIME/AT THE SAME TIMEtogether, at the same time 一起，同时 I can’t do two things at once! 我不能同时做两件事！ Don’t all talk at once. 不要同时发言。 RegisterIn everyday English, when people mean 'immediately', they usually say right away or, in British English, straight away rather than at once: 在日常英语中，人们表示 “立刻” 时一般说right away或straight away(英国英语)，而不说at onceI recognized him right away. 我立刻认出了他。6  once more/once again AGAIN a) again, after happening several times before 再次〔发生〕，又一次 I looked at myself in the mirror once more. 我再看了一眼镜子里的自己。 Once again she’s refusing to help. 她再一次拒绝帮助。 b) used to say that a situation changes back to its previous state 再次〔回到原来状态〕 The crowds had all gone home and the street was quiet once more. 众人都回家去了，街上恢复了宁静。 c) formal used before you repeat something that you said before 再说一次，重复说一遍 Once again, it must be stressed that the pilot was not to blame. 再说一遍，必须强调的是飞行员没有责任。7  all at once a) SUDDENLYif something happens all at once, it happens suddenly when you are not expecting it 一下子，突然 All at once there was a loud banging on the door. 突然传来一记重重的敲门声。 b) together, at the same time 一起，同时 A lot of practical details needed to be attended to all at once. 许多实际上的细节问题都需要同时处理。8  (every) once in a while SOMETIMESsometimes, although not often 偶尔，有时，间或 I do get a little anxious once in a while. 我的确偶尔会有点焦虑。 I saw her in the shop every once in a while. 有时我在商店里看到她。9  never once/not once used to emphasize that something has never happened 从未，从来没有 I never once saw him get angry or upset. 我从未见过他生气或不快。 Not once did they finish a job properly. 他们从来没有把一件事情做好过。10  (just) for once RARELYused to say that something unusual happens, especially when you wish it would happen more often 难得一次，就这一回 Be honest for once. 诚实点，哪怕就这一次。 Just for once, let me make my own decision. 就这一次让我自己作决定吧。 For once Colin was speechless. 科林这一次无话可说。11  once and for all a) CHANGE/MAKE something DIFFERENTif you deal with something once and for all, you deal with it completely and finally 彻底地，一劳永逸地 Let’s settle this matter once and for all. 我们把这个问题彻底解决了吧。 b) British English spokenTELL/ORDER somebody TO DO something used to emphasize your impatience when you ask or say something that you have asked or said many times before 最后一次〔强调不耐烦〕 Once and for all, will you switch off that television! 最后说一次，把那电视关掉！12  once or twice FEW/NOT MANYa few times 一两次，几次 I wrote to him once or twice, but he didn’t answer. 我给他写过一两次信，但他没有回复。13  (just) this once spokenONLY used to emphasize that this is the only time you are allowing something, asking for something etc, and it will not happen again 就这一次 Go on, lend me the car, just this once. 好啦，把车借给我吧，就这一次。 I’ll make an exception this once. 这次我就破个例。14  once upon a time a) spokenPAST at a time in the past that you think was much better than now 以前，从前，那时候〔指比现在好得多的过去某一时期〕 Once upon a time you used to be able to leave your front door unlocked. 从前，大门是可以不上锁的。 b) RFa long time ago – used at the beginning of children’s stories 从前，很久以前〔用于儿童故事的开头〕15  once in a blue moon informalRARELY very rarely 难得地，破天荒地 It only happens like this once in a blue moon. 这样的情况是极为罕见的。16  do something once too often HARM/BE BAD FORto repeat a bad, stupid, or dangerous action with the result that you get punished or cause trouble for yourself 屡次做坏事[傻事，危险之事]而遭殃 He tried that trick once too often and in the end they caught him. 他一次次故伎重施，最后他们终于把他抓住了。17  once a ..., always a ...always a ... once a ... spoken used to say that people stay the same and cannot change the way they behave and think 一次是…就永远是…〔表示一个人的品性是无法改变的〕 Once a thief, always a thief. 一日为贼，终生是贼。18. once is/was enough spoken used to say that after you have done something one time you do not need or want to do it again 一次就够了〔表示你不需要或不想再做了〕19. once bitten, twice shytwice shy once bitten NOT DO somethingused to say that people will not do something again if it has been a bad experience 一朝被蛇咬，十年怕井绳

Examples from the Corpus

once• Some were hit more than once.• Here's a picture of a convertible we had once.• I've only worn this dress once.• The school funding proposed by Wilson this year is once again the minimum required by school funding.• In seventh grade, the problem increased once again, with nearly 22 percent of students identified as work-inhibited.• The invisible flutter and swoop of black creatures, still furious with the woman who had once banished them.• Nomatterhow he had changed - if indeed he had changed - that man had once been a sadistic brute.• She once called me a liar - I've never forgiven her.• It will be opened to the public in the next few years, once essential maintenance is completed.• I remember once it snowed on my birthday, and I was so excited.• You once let out the fact that you wished you were free of the burdens your family placed on you.• Brush tops with garlic oil and turn once more.• They had met once on holiday, so they knew each other slightly.• Once, when I was a little boy, I found a gold watch on the beach.(just) the once• I'd say go, even if it's only just the once.• Vauxhall, George Smith: an ornamental design echoing the wrought-iron work of the once famous Vauxhall Gardens.• And it was here that the once great motorbike manufacturers of the Midlands tested the machines that are still running today.• An example is the once highly popular low-carbohydrate method of slimming.• So what now for the once mighty Gingrich?• What had happened to the once mighty race which had built this superior piece of engineering?• Maybe, but the once pricey products that use this satellite technology have come down to earth.once2 ●●● S1 W1 conjunction  HAPPENfrom the time when something happens 一…便，一旦，一经 Once I get him a job, he’ll be fine. 一旦我帮他找到了工作，他就会好的。 Once in bed, the children usually stay there. 孩子们一旦上了床，一般就不下来了。

Examples from the Corpus

once• I called Lara once he'd left.• Once in the US, the drugs are distributed to all the major cities.Origin once1 (1200-1300) one

once1 adverb →10-19
→REGISTER1once2 conjunctionChinese  

Corpus on occasion only one

once

I

once¹ S1 W1 /wʌns/ adverb1. on one occasion only:
    I’ve only met her once.
    Paul’s been to Wexford once before.
    (just) the once British English spoken:
    Mrs Peterson came in to see Ruth just the once.
2. once a week/once every three months etc one time every week etc, as a regular activity or event:
    Staff meetings take place once a week.
    They took separate holidays at least once every two years.
3. at some time in the past, but not now:
    Sonya and Ida had once been close friends.
    She and her husband had once owned a house like this.
    once-great/proud etc
    It was sad to see the once-great man looking so frail.
    the once-mighty steel industry
4. in the past, at a time that is not stated:
    I once ran 21 miles.
    Marx once described religion as the ‘opium of the people’.
5. at once
  a. immediately or without delay:
    Now, go upstairs at once and clean your room!
    When I saw him I recognized him at once.
  b. together, at the same time:
    I can’t do two things at once!
    Don’t all talk at once.
  REGISTER
    In everyday English, when people mean 'immediately', they usually say right away or, in British English, straight away rather than at once:
   ▪ I recognized him right away.
6. once more/once again
  a. again, after happening several times before:
    I looked at myself in the mirror once more.
    Once again she’s refusing to help.
  b. used to say that a situation changes back to its previous state:
    The crowds had all gone home and the street was quiet once more.
  c. formal used before you repeat something that you said before:
    Once again, it must be stressed that the pilot was not to blame.
7. all at once
  a. if something happens all at once, it happens suddenly when you are not expecting it:
    All at once there was a loud banging on the door.
  b. together, at the same time:
    A lot of practical details needed to be attended to all at once.
8. (every) once in a while sometimes, although not often:
    I do get a little anxious once in a while.
    I saw her in the shop every once in a while.
9. never once/not once used to emphasize that something has never happened:
    I never once saw him get angry or upset.
    Not once did they finish a job properly.
10. (just) for once used to say that something unusual happens, especially when you wish it would happen more often:
    Be honest for once.
    Just for once, let me make my own decision.
    For once Colin was speechless.
11. once and for all
  a. if you deal with something once and for all, you deal with it completely and finally:
    Let’s settle this matter once and for all.
  b. British English spoken used to emphasize your impatience when you ask or say something that you have asked or said many times before:
    Once and for all, will you switch off that television!
12. once or twice a few times:
    I wrote to him once or twice, but he didn’t answer.
13. (just) this once spoken used to emphasize that this is the only time you are allowing something, asking for something etc, and it will not happen again:
    Go on, lend me the car, just this once.
    I’ll make an exception this once.
14. once upon a time
  a. spoken at a time in the past that you think was much better than now:
    Once upon a time you used to be able to leave your front door unlocked.
  b. a long time ago – used at the beginning of children’s stories
15. once in a blue moon informal very rarely:
    It only happens like this once in a blue moon.
16. do something once too often to repeat a bad, stupid, or dangerous action with the result that you get punished or cause trouble for yourself:
    He tried that trick once too often and in the end they caught him.
17. once a ..., always a ... spoken used to say that people stay the same and cannot change the way they behave and think:
    Once a thief, always a thief.
18. once is/was enough spoken used to say that after you have done something one time you do not need or want to do it again
19. once bitten, twice shy used to say that people will not do something again if it has been a bad experience

II

once² S1 W1 conjunction
from the time when something happens:
    Once I get him a job, he’ll be fine.
    Once in bed, the children usually stay there.