once

I. once¹ S1 W1 /wʌns/ BrE AmE adverb
[Date: 1200-1300; Origin: one]
1. 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

Oxford Advanced Learner's Dictionary

once

once adverb, conjunction [wʌns] [wʌns]

adverb
1. on one occasion only; one time
• I've only been there once.
• He cleans his car once a week.
• She only sees her parents once every six months.

• (informal) He only did it the once.

2. at some time in the past
• I once met your mother.
• He once lived in Zambia.

• This book was famous once, but nobody reads it today.

3. used in negative sentences and questions, and after if to mean ‘ever’ or ‘at all’
• He never once offered to help.
• If she once decides to do something, you won't change her mind.
Word Origin:
Middle English ones, genitive of one. The spelling change in the 16th cent. was in order to retain the unvoiced sound of the final consonant.

Idioms: all at once ▪ at once ▪ for once ▪ going once, going twice, sold ▪ just this once ▪ once a …, always a … ▪ once again ▪ once and for all ▪ once bitten, twice shy ▪ once in a blue moon ▪ once in a while ▪ once more ▪ once or twice ▪ once too often ▪ once upon a time

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

once / wʌns / adverb (ONE TIME)

A2 one single time:

I went sailing once, but I didn't like it.

We have lunch together once a month.

at once C1 at the same time:

They all started talking at once.

for once B2 used when something happens that does not usually happen:

For once, the bus came on time.

just this once used to say that you will only do or request something on this particular occasion:

All right, I'll give you a lift - just this once.

once again ( also once more ) B1 again, as has happened before:

Once again, racist attacks are increasing across Europe.

once more B1 one more time:

I'd like to visit the colleges once more before we leave.

again, as has happened before:

I'm pleased that Daniel's working with us once more.

once or twice a few times:

I've seen him once or twice in town.

(every) once in a while B2 sometimes but not often:

We meet for lunch once in a while.

once and for all C2 completely and in a way that will finally solve a problem:

Our intention is to destroy their offensive capability once and for all.

once in a lifetime only likely to happen once in a person's life:

An opportunity as good as this arises once in a lifetime.

→ See also once-in-a-lifetime

the once on a single occasion:

I've only played rugby the once, and I never want to play it again.

once / wʌns / adverb (PAST)

B1 in the past, but not now:

This house once belonged to my grandfather.

Computers are much cheaper nowadays than they once were.

Once-thriving villages stand deserted and in ruins.

Collins Advanced Learner’s English Dictionary

once

/wʌns/

Frequency: The word is one of the 700 most common words in English.

1.
If something happens once, it happens one time only.
I met Wilma once, briefly...
Since that evening I haven’t once slept through the night...
Mary had only been to Manchester once before.
ADV: ADV with v
•
Once is also a pronoun.
‘Have they been to visit you yet?’—‘Just the once, yeah.’...
Listen to us, if only this once.
PRON: the/this PRON

2.
You use once with ‘a’ and words like ‘day’, ‘week’, and ‘month’ to indicate that something happens regularly, one time in each day, week, or month.
Lung cells die and are replaced about once a week...
We arranged a special social event once a year to which we invited our major customers.
ADV: ADV a n

3.
If something was once true, it was true at some time in the past, but is no longer true.
The culture minister once ran a theatre...
I lived there once myself, before I got married...
The house where she lives was once the village post office...
My memory isn’t as good as it once was.
ADV: ADV with v, ADV with be, ADV with group/cl

4.
If someone once did something, they did it at some time in the past.
I once went camping at Lake Darling with a friend...
We once walked across London at two in the morning...
Diana had taken that path once.
ADV: ADV with v

5.
If something happens once another thing has happened, it happens immediately afterwards.
The decision had taken about 10 seconds once he’d read a market research study...
Once customers come to rely on these systems they almost never take their business elsewhere...
CONJ

6.
If something happens all at once, it happens suddenly, often when you are not expecting it to happen.
All at once there was someone knocking on the door.
= all of a sudden
PHRASE: PHR with cl

7.
If you do something at once, you do it immediately.
I have to go, I really must, at once...
Remove from the heat, add the parsley, toss and serve at once...
The audience at once greeted him warmly.
= immediately
PHRASE: PHR with v

8.
If a number of different things happen at once or all at once, they all happen at the same time.
You can’t be doing two things at once...
No bank could ever pay off its creditors if they all demanded their money at once...
PHRASE: PHR after v, PHR adj/n and adj/n

9.
For once is used to emphasize that something happens on this particular occasion, especially if it has never happened before, and may never happen again.
For once, dad is not complaining...
His smile, for once, was genuine.
PHRASE: PHR with cl [emphasis]

10.
If something happens once again or once more, it happens again.
Amy picked up the hairbrush and smoothed her hair once more...
Once again an official inquiry has spoken of weak management and ill-trained workers.
PHRASE: PHR with v, PHR with cl

11.
If something happens once and for all, it happens completely or finally.
We have to resolve this matter once and for all...
If we act fast, we can once and for all prevent wild animals in Britain from suffering terrible cruelty.
PHRASE: PHR with v [emphasis]

12.
If something happens once in a while, it happens sometimes, but not very often.
Earrings need to be taken out and cleaned once in a while.
= occasionally
PHRASE: PHR with cl

13.
If you have done something once or twice, you have done it a few times, but not very often.
I popped my head round the door once or twice...
Once or twice she had caught a flash of interest in William’s eyes...
PHRASE: PHR with cl, PHR with v

14.
Once upon a time is used to indicate that something happened or existed a long time ago or in an imaginary world. It is often used at the beginning of children’s stories.
‘Once upon a time,’ he began, ‘there was a man who had everything.’...
Once upon a time, asking a woman if she has a job was quite a straightforward question.
PHRASE: PHR with cl

Merriam-Webster's Advanced Learner's Dictionary

¹once /ˈwʌns/ adv
1 : one time only
• I will repeat the question once.
• We try to get together (at least) once every month.
• The play was performed only once.
• He had ridden a horse only once (before).
• We go to the movies once or twice a month. [=we go to the movies a few times a month]
• I've only seen her once or twice. [=I have only seen her a few times]
2 : at any one time : ever
• She didn't once thank me.
• He didn't look at me once.
3 : at some time in the past
• It was once done that way.
• A river once flowed through this canyon.
• It was once a booming mining town.
• Their music was once very popular.
- sometimes used in combination
• a once-successful actor
• a once-popular restaurant
once again/more : for another time : one more time : again
• Let me explain the problem once again.
• Once again, you've ignored my instructions.
• Could I hear the question once more?
once and for all : now and for the last time
• Let's settle this problem once and for all.
• Winning its fourth straight championship game, the team proved once and for all that they are the best.
• I'm asking you once and for all.
• Please, once and for all, stop worrying.
once bitten, twice shy
- see ¹bite
once in a blue moon
- see blue moon
once in a while : sometimes but not often : occasionally
• We spend most of our time at home and go out once in a while.
• Every once in a while, we have wine with dinner.
once upon a time : at some time in the past
• He was a famous actor once upon a time.
✦Once upon a time is the traditional way to begin a fairy tale.
• Once upon a time, there was a beautiful princess named Snow White.