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English definition of “sure”

sure

adjective uk   /ʃɔːr/ us    /ʃʊr/
A2 certain; without any doubt: "What's wrong with him?" "I'm not really sure." I'm sure (that) I left my keys on the table. I feel absolutely sure (that) you've made the right decision. It now seems sure (that) the election will result in another victory for the government. Simon isn't sure whether/if he'll be able to come to the party or not. Is there anything you're not sure of/about? There is only one sure way (= one way that can be trusted) of finding out the truth.
See also
be sure of/about sb to have confidence in and trust someone: Henry has only been working for us for a short while, and we're not really sure about him yet. You can always be sure of Kay. for sure B1 certain or certainly: I know for sure that I won't be able to go to the party. One thing's for sure - once the baby's born, your lives will never be the same again. be sure of yourself B2 to be very or too confident: She's become much more sure of herself since she got a job. be sure of sth B2 be confident that something is true: He said that he wasn't completely sure of his facts. be sure of getting/winning sth to be certain to get or win something: We arrived early, to be sure of getting a good seat. A majority of Congress members wanted to put off an election until they could be sure of winning it. be sure to C1 to be certain to: She's sure to win. I want to go somewhere where we're sure to have good weather. make sure (that) A2 to look and/or take action to be certain that something happens, is true, etc.: Make sure you lock the door behind you when you go out. If you have a sure knowledge or understanding of something, you know or understand it very well: I don't think he has a very sure understanding of the situation.

sure

adverb uk   /ʃɔːr/ us    /ʃʊr/ informal
A2 certainly: "Do you want to come swimming with us?" "Sure."mainly US "Will you help me with this?" "Sure I will."US I sure am hungry.
(Definition of sure from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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