[ shoor, shur ]
See synonyms for: suresurestsureness on

adjective,sur·er, sur·est.
  1. free from doubt as to the reliability, character, action, etc., of something: to be sure of one's data.

  2. confident, as of something expected: sure of success.

  1. convinced, fully persuaded, or positive: to be sure of a person's guilt.

  2. assured or certain beyond question: a sure victory.

  3. worthy of confidence; reliable; stable: a sure messenger.

  4. unfailing; never disappointing expectations: a sure cure.

  5. unerring; never missing, slipping, etc.: a sure aim.

  6. admitting of no doubt or question: sure proof.

  7. destined; bound inevitably; certain: sure death.

  8. Obsolete. secure; safe.

  9. be sure, to take care (to be or do as specified); be certain: Be sure to close the windows.

  1. Informal. certainly; surely: It sure is cold out. Sure, I'll come.

Idioms about sure

  1. for sure, as a certainty; surely: It's going to be a good day, for sure.

  2. make sure, to be or become absolutely certain: I'm calling to make sure that you remember to come.

  1. sure enough, Informal. as might have been supposed; actually; certainly: Sure enough, the picnic was rained out.

  2. to be sure,

    • without doubt; surely; certainly.

    • admittedly: She sings well, to be sure, but she can't act.

Origin of sure

First recorded in 1300–50; Middle English sur(e), from Middle French sur,Old French seur, from Latin sēcūrus “carefree”; see secure

confusables note For sure

Both sure and surely are used as intensifying adverbs with the sense “undoubtedly, certainly.” In this use, sure is generally informal and occurs mainly in speech and written representations of speech: She sure dazzled the audience with her acceptance speech. It was sure hot enough in the auditorium. Surely is used in this sense in all varieties of speech and writing, even the most formal: The court ruled that the law was surely meant to apply to both profit-making and nonprofit organizations. See also quick, slow.

Other words from sure

  • sureness, noun
  • o·ver·sure, adjective
  • o·ver·sure·ly, adverb
  • o·ver·sure·ness, noun
  • un·sure, adjective
  • un·sure·ly, adverb
  • un·sure·ness, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use sure in a sentence

British Dictionary definitions for sure


/ (ʃʊə, ʃɔː) /

  1. (sometimes foll by of) free from hesitancy or uncertainty (with regard to a belief, conviction, etc): we are sure of the accuracy of the data; I am sure that he is lying

  2. (foll by of) having no doubt, as of the occurrence of a future state or event: sure of success

  1. always effective; unfailing: a sure remedy

  2. reliable in indication or accuracy: a sure criterion

  3. (of persons) worthy of trust or confidence: a sure friend

  4. not open to doubt: sure proof

  5. admitting of no vacillation or doubt: he is very sure in his beliefs

  6. bound to be or occur; inevitable: victory is sure

  7. (postpositive) bound inevitably (to be or do something); certain: she is sure to be there tonight

  8. physically secure or dependable: a sure footing

  9. obsolete free from exposure to harm or danger

  10. be sure (usually imperative or dependent imperative; takes a clause as object or an infinitive, sometimes with to replaced by and) to be careful or certain: be sure and shut the door; I told him to be sure to shut the door

  11. for sure without a doubt; surely

  12. make sure

    • (takes a clause as object) to make certain; ensure

    • (foll by of) to establish or confirm power or possession (over)

  13. sure enough informal as might have been confidently expected; definitely: often used as a sentence substitute

  14. to be sure

    • without doubt; certainly

    • it has to be acknowledged; admittedly

  1. (sentence substitute) informal willingly; yes

  2. (sentence modifier) informal, mainly US and Canadian without question; certainly

Origin of sure

C14: from Old French seur, from Latin sēcūrus secure

Derived forms of sure

  • sureness, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Idioms and Phrases with sure


In addition to the idioms beginning with sure

  • sure as shooting
  • sure cure
  • sure enough
  • sure of oneself
  • sure thing

also see:

  • for certain (sure)
  • make sure
  • slow but sure
  • to be sure

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.