Etymology: Middle English seur, sure, from Anglo-French seur, from Latin securus secure
Date: 13th century
1. obsolete safe from danger or harm
2. firmly established ; steadfast <a sure hold> 3. reliable, trustworthy <a sure friend> 4. a. marked by or given to feelings of confident certainty <I'm sure I'm right> b. characterized by a lack of wavering or hesitation <sure brush strokes> <a sure hand> 5. admitting of no doubt ; indisputable <spoke from sure knowledge> 6. a. bound to happen ; inevitable <sure disaster> b. bound, destined <is sure to win> 7. careful to remember, attend to, or find out something <be sure to lock the door> • sureness noun Synonyms: sure, certain, positive, cocksure mean having no doubt or uncertainty. sure usually stresses the subjective or intuitive feeling of assurance <felt sure that I had forgotten something>. certain may apply to a basing of a conclusion or conviction on definite grounds or indubitable evidence <police are certain about the cause of the fire>. positive intensifies sureness or certainty and may imply opinionated conviction or forceful expression of it <I'm positive that's the person I saw>. cocksure implies presumptuous or careless positiveness <you're always so cocksure about everything>. II. adverb Date: 14th century surely Usage: Most commentators consider the adverb sure to be something less than completely standard; surely is usually recommended as a substitute. Our current evidence shows, however, that sure and surely have become differentiated in use. Sure is used in much more informal contexts than surely. It is used as a simple intensive <I can never know how much I bored her, but, be certain, she sure amused me — Norman Mailer> and, because it connotes strong affirmation, it is used when the speaker or writer expects to be agreed with <it's a moot point whether politicians are less venal than in Twain's day. But they're sure as the devil more intrusive — Alan Abelson> <he sure gets them to play — D. S. Looney>. Surely, like sure, is used as a simple intensive <I surely don't want to leave the impression that I had an unhappy childhood — E. C. Welsh> but it occurs in more formal contexts than sure. Unlike sure it may be used neutrally—the reader or hearer may or may not agree <it would surely be possible, within a few years, to program a computer to construct a grammar — Noam Chomsky> and it is often used when the writer is trying to persuade <surely a book on the avant-garde cannot be so conventional — Karl Shapiro>.
New Collegiate Dictionary. 2001.