sure, certain, positive, cocksure mean having no doubt or uncertainty. sure usually stresses the subjective or intuitive feeling of assurance. certain may apply to a basing of a conclusion or …

CERTAIN definition: 1. having no doubt or knowing exactly that something is true, or known to be true, correct, exact…. Learn more.

for certain, without a doubt; surely: I know for certain that I have seen that face before.

If you say that something is certain, you firmly believe that it is true, or have definite knowledge about it.

4 days ago · certain (comparative more certain or certainer, superlative most certain or certainest) Sure in one's mind, positive; absolutely confident in the truth of something.

1. (postpositive) positive and confident about the truth of something; convinced: I am certain that he wrote a book. 2. (usually postpositive) definitely known: it is certain that they were on the …

[before a noun] (used before a person or thing that is known in the mind of the speaker or writer, but that is being introduced to the listener): A certain Mr. Smith has been trying to meet you.

From Middle English certain, certein, from Old French certain, from Vulgar Latin unattested form *certānus, extended form of Latin certus (“fixed, resolved, certain”), of the same origin as …

"what is certain is that every effect must have a cause"; "it is certain that they were on the bus"; "his fate is certain"; "the date for the invasion is certain"

Certain can mean "definite" or "sure to happen," like getting wet, a certain outcome of not having an umbrella in a rainstorm. It can also refer to a particular person or thing.