From Middle English sure, sur, from Middle French sur, from Old French seür, from Latin sēcūrus (“secure”, literally “carefree”), from se (“apart”) + cura (“care”) (compare Old English orsorg (“carefree”), from or (“without”) + sorg (“care”)). See cure. Displaced native Middle English wis, iwis (“certain, sure”) (from Old English ġewis, ġewiss (“certain, sure”)), Middle English siker (“sure, secure”) (from Old English sicor (“secure, sure”)).
- (RP) IPA: /ʃʊə(ɹ)/, /ʃɔː(ɹ)/, X-SAMPA: /SU@(r\)/, /SO:(r\)
- Rhymes: -ʊə(r), -ɔː(r)
- (GenAm) IPA: /ʃʊɹ/, /ʃɔɹ/, /ʃɝ/, X-SAMPA: /SUr\/, /SOr\/, /S3'/
Audio (US) (file)
- (Australia, New Zealand) IPA: /ʃoː(ɹ)/, X-SAMPA: /So:(r\)/
- Homophones: shaw, Shaw (in some non-rhotic dialects); shore (in some dialects)
- Physically secure and certain, non-failing, reliable.
- This investment is a sure thing.
- The bailiff had a sure grip on the prisoner's arm.
- Certain in one's knowledge or belief.
- He was sure she was lying.
- I am sure of my eventual death.
- John was acting sure of himself but in truth had doubts.
- Certain to act or be a specified way.
- Be sure to lock the door when you leave.
- (secure and steadfast): certain, failsafe, reliable
- (steadfast in one's knowledge or belief): certain, positive, wis
Derived terms 
- (modal adverb) Without doubt.
- Sure he's coming! Why wouldn't he?
- "Did you kill that bear yourself? ―"I sure did!"
Usage notes 
- 1996, T.F. Hoad, The Concise Oxford Dictionary of Etymology, Oxford University Press, ISBN 0192830988
- definite and plural of sur
- Indicative present connegative form of surra.
- Second-person singular imperative present form of surra.
- Second-person singular imperative present connegative form of surra.
- feminine form of sur
Old English 
From Germanic, related to sūr (“sour”).
- IPA: /ˈsuːre/
- Inflected form of sur
- absolute definite natural masculine form of sur.
From Arabic سورة (sūra).