sure / shoŏr/ • adj. confident in what one thinks or knows; having no doubt that one is right: I'm sure I've seen that dress before she had to check her diary to be sure of the day of the week. ∎  (sure of) having a certain prospect or confident anticipation of: Ripken can be sure of a place in the Hall of Fame. ∎  certain to do something: it's sure to rain before morning. ∎  true beyond any doubt: what is sure is that learning is a complex business. ∎  able to be relied on or trusted: her neck was red—a sure sign of agitation. ∎  confident; assured: the drawings impress by their sure sense of rhythm.• adv. inf. certainly (used for emphasis): Texas sure was a great place to grow up. ∎  [as interj.] used to show assent: “Are you serious?” “Sure.”PHRASES: be sure do not fail (used to emphasize an invitation or instruction): be sure to drop by | be sure that you know what is required. for sure inf. without doubt: I can't say for sure what George really wanted.make sure establish that something is definitely so; confirm: go and make sure she's all right. ∎  ensure that something is done or happens: he made sure that his sons were well educated.sure enough inf. used to introduce a statement that confirms something previously predicted: when X-rays were taken, sure enough, there was the needle.sure of oneself very confident of one's own abilities or views: he's very sure of himself.sure thing inf. a certainty. ∎  [as interj.] certainly; of course: “Can I watch?” “Sure thing.”to be sure used to concede the truth of something that conflicts with another point that one wishes to make: the ski runs are very limited, to be sure, but excellent for beginners. ∎  used for emphasis: what an extraordinary woman she was, to be sure.DERIVATIVES: sure·ness n.ORIGIN: Middle English: from Old French sur, from Latin securus ‘free from care.’

sure †safe, secure XIV–XVII; trustworthy, steadfast XIV; subjectively certain XIV; objectively certain XV. — OF. sur(e) (mod. sûr) :- L. sēcūrus SECURE.
So surety †safety, security, certainty; bond entered into for the performance of an undertaking XIV; person undertaking this, bail XV. — OF. surte (mod. sûreté) :- L. sēcuritās, -tät- SECURITY; see -TY2. Whence suretyship XVI.