| 1. | something that is or is supposed to be a certain success, as a bet or a business venture: He thinks that real estate is a sure thing. |
| 2. | something assured; certainty: It's a sure thing that he'll refuse to cooperate. |
| 3. | surely; for sure; O.K.; roger (often used as an interjection). |

| sure thing n. An outcome that is certain or assured; a certainty: "Any respectable contrarian is tempted to think a recession is a sure thing" (Floyd Norris). interj. Informal Of course; certainly: Sure thing, I'll be there! |
sure thing
a sure thing. A certainty, as in Making the bestseller list has been a sure thing for Stephen King. This usage originally alluded to a bet that one could not lose. [First half of 1800s]
Yes indeed, certainly, as in Are you coming tonight?
Sure thing! This use of the idiom as an interjection dates from the late 1800s.