one - definition and synonyms

determiner, number, pronoun 

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One can be used in the following ways:
as a number: We have only one child.How much does one pound of apples cost?
as a determiner: He grew roses on one side of his garden, and vegetables on the other.We’ll meet again one day.
as a pronoun (the plural of this pronoun is ones and the possessive is one’s): It’s a good book, but his last one was better.One has to trust one’s family.They are the ones who suffered. (followed by ‘of’): Sydney is one of the world’s most exciting cities.
  1. 1
    the number 1

    I’ve only got one hour free.

    They have one daughter and five sons.

    Over one hundred people were killed in the disaster.

    It was a one-storey building with big windows.

  2. 2
    used for referring to a single person or thing when there are others of the same type

    I bought three T-shirts – do you want one?

    One passenger said she had been waiting for 13 hours.

    I heard of one case where a 12-year-old boy had been sent to prison.

    one of:

    Ours was one of the top four boats in the competition.

    One of the buildings was badly damaged in the fire.

    I met one of her brothers when he was here on business.

    just the one:

    ‘How many books did she borrow?’ ‘Just the one.’

  3. 3
    used for referring to something when that type of thing has already been mentioned or when it is obvious what type of thing you are talking about

    It was a problem, but not a major one.

    I’m only using this radio until I can buy a better one.

    Your experiences are ones that are shared by countless other parents.

    the one/ones:

    I’m going to keep those boxes. The ones I want to get rid of are in the garage.

    this one/that one/these ones/those ones:

    I’d never seen a game like that one.

    1. a.
      used for referring to a particular joke, comment, idea, or question

      You want me to say how much freedom students should have? That’s a tricky one.

      the one about (=the joke about someone or something):

      Did you hear the one about the American who goes into a bar in Paris?

  4. 4
    used for referring to someone when they have been mentioned before or when it is obvious which person you are talking about
    the one/ones:

    David and I are the only ones left who are not married.

    They were all dealing drugs, but Bob was the one who got caught.

    Who is the one with the beard?

    1. a.
      people of a particular type
      the young/clever/lucky etc ones:

      The clever ones always come out on top.

    2. b.
      formal used instead of ‘someone’

      I speak as one who has seen much suffering.

  5. 5
    formal used instead of ‘you’ when you are making a statement about people in general, which also applies to yourself

    Why, one may ask, would someone want to burn down their own house?

    One cannot always be right, can one?

    One must bring one’s own talents to every single task.

    One cannot be sure what lies ahead.

  6. 6
    the only person or thing of a particular type
    the one:

    She found herself in the one spot that gave her no shelter from the rain.

    We’re going to have to play the one team we did not want to play.

    1. a.
      used for emphasizing that something is someone’s only hope, disappointment, fear etc
      the one:

      The one disappointment we had was that we didn’t get to shake hands with the President.

      someone’s one hope/fear/concern etc:

      My one hope is that more people with disabilities will enter into professions like social work.

  7. 7
    used for emphasizing a particular fact, person, or thing

    There’s one thing you can be sure of – you won’t get any help from the government.

    One person who won’t be invited is that awful man who lives downstairs.

    1. a.
      mainly American informal used for emphasizing that someone or something is a particular type of person or thing

      He’s one proud man, I’ll tell you.

  8. 8
    used for mentioning the first of two or more similar people or things, especially when you are comparing them
    one... the other:

    She lay on the sofa with a glass in one hand and an empty bottle in the other.

    If you love both children, I don’t understand why you give so much to one and not the other.

    one... another:

    He could not tell the difference between one flower and another.

  9. 9
    formal used before someone’s name when you do not know them or have not met them before

    I borrowed the money from one Edward Ashley.

  10. 10
    informal a glass of alcoholic drink

    Have you got time for a quick one before you go?

    See also road