American English

Definition of one number from the Oxford Advanced American Dictionary



    number, determiner
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  1. 1the number 1 Do you want one or two? There's only room for one person. One more, please! a one-bedroom apartment I'll see you at one (= one o'clock).
  2. 2used in formal language or for emphasis before hundred, thousand, etc., or before a unit of measurement It cost one hundred and fifty dollars. He lost by less than one second.
  3. 3used for emphasis to mean “a single” or “just one” There's only one thing we can do.
  4. 4a person or thing, especially when they are part of a group One of my friends lives in Boston. One place I'd really like to visit is Bali.
  5. 5used for emphasis to mean “the only one” or “the most important one” He's the one person I can trust. Her one concern was for the health of her baby. It's the one thing I can't stand about him.
  6. 6used when you are talking about a time in the past or the future, without actually saying which one I saw her one afternoon last week. One day (= at some time in the future) you'll understand.
  7. 7the same They all went off in one direction.
  8. 8(informal) used for emphasis instead of a or an That was one hell of a game! She's one snazzy dresser.
  9. 9used with a person's name to show that the speaker does not know the person synonym a certain He worked as an assistant to one Jonathan Jones.
  10. Idioms having two or more uses, functions, etc. It's a corkscrew and bottle opener all in one.
    as one (formal)
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    in agreement; all together We spoke as one on this matter.
    (be) at one (with somebody/something) (formal)
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    to feel that you completely agree with someone or something, or that you are part of something a place where you can feel at one with nature
    back to square one
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    a return to the situation you were in at the beginning of a project, task, etc., because you have made no real progress If this suggestion isn't accepted, we'll be back to square one.
    be a minority of one (often humorous)
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    to be the only person to have a particular opinion or to vote a particular way
    used to emphasize that a particular person does something and that you believe other people do too I, for one, would prefer to postpone the meeting.
    get one over (on) somebody/something (informal)
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    to get an advantage over someone or something I'm not going to let them get one over on me!
    go one better (than somebody/something)
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    to do something better than someone else or than you have done before synonym outdo She did well this year and next year she hopes to go one better.
    used to say that someone or something has different roles, contains different things, or is used for different purposes She's a mother and successful career woman in one. It's a public relations office, a press office, and a private office all in one. see also all-in-one
    once/when you've seen, heard, etc. one, you've seen, heard, etc. them all (saying)
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    used to say that all types of the things mentioned are very similar I don't like science fiction novels much. Once you've read one, you've read them all.
    one after another/the other
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    first one person or thing, and then another, and then another, up to any number or amount The bills kept coming in, one after another.
    one and all (old-fashioned) (informal)
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    everyone Happy New Year to one and all!
    one and only
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    used to emphasize that someone is famous Here he is, the one and only Van Morrison!
    one and the same
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    used for emphasis to mean “the same” I never realized Ruth Rendell and Barbara Vine were one and the same (= the same person using two different names).
    separately and in order I went through the items on the list one by one. a few We've had one or two problems—nothing serious.
    one up (on somebody)
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    having an advantage over someone
See the Oxford Advanced Learner's Dictionary entry: one