sure - definition and synonyms


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  1. 1
    certain that something is real, true, or correct

    I think she’s called Monica, but I’m not sure.

    sure (that):

    Are you sure these figures are right?

    sure (that):

    I was sure that I had left my keys on the counter.

    sure about:

    If you’re really sure about the facts, we’ll publish them.

    sure how/why/if etc:

    No one is really sure why he resigned.

    pretty sure (=fairly certain):

    I’m pretty sure the pool is open until 6.00.

    1. a.
      certain about what you feel, what you want, or what you have decided

      ‘I’ll take the blue one.’ ‘Are you sure?’

      not sure how/why/where etc:

      They’re not really sure where they want to live.

      quite/absolutely sure:

      I’ll certainly support you, if you’re quite sure that this is what you want.

    2. b.
      confident and not in any doubt about something
      sure of:

      If you’re not sure of the answers, say so.

      sure of yourself:

      He sounded so sure of himself that I began to believe him.

      feel sure (that):

      I felt sure I could do it if only they’d give me a chance.

  2. 2
    certain to happen or to result from something
    sure to do something:

    If you get drunk tonight, you’re sure to feel rotten in the morning.

    a sure thing/bet (=something that will definitely happen):

    Everyone thought it was a sure thing, and we were amazed when they pulled out.

    for sure:

    One thing is for sure, I’m never going skydiving again!

    1. a.
      [usually before noun] formal certain to succeed

      He took sure aim and squeezed the trigger.

      a sure path to success

  3. 4
    used about something that is definite and cannot be questioned or doubted

    a sure command of the facts

    a sure memory for names

    a sure sign/indication (=a clear and definite sign that something is true):

    The increase in new home sales is a sure sign the recession is over.

derived word


noun [uncountable]