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English definition of “sure”

sure

adjective [-er/-est only]    /ʃʊər/  /ʃoʊr/
certain; without any doubt: "No more dessert for me, thank you." "Are you sure?" [+ (that) clause] I’m sure (that) I left my keys on the table. [+ question word] I’m not sure where they live. If there’s anything you’re not sure of/about, just ask. He said that he wasn’t completely sure of his facts (= not certain that his information was correct). We arrived early, to be sure of getting a good seat. [+ to infinitive] She’s sure to win. If you are sure of yourself, you are confident: She’s much more sure of herself since she started work.
(Definition of sure adjective from the Cambridge Academic Content Dictionary © Cambridge University Press)
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