Meaning of CERTAIN in English
(IN NO DOUBT) [adjective] - having no doubt or knowing exactly (that something is true), or known to be true, correct, exact or effective"I won't have any more cake, thank you." "Are you certain?""Are you going to Karl's party?" "I'm not certain yet."I'm certain (that) he'll go, because he's already bought a ticket.It's quite certain (that) he'll go.Are you absolutely certain (that) they heard your warning?I feel certain (that) you're doing the right thing.You should make certain (that) no one else has already done that.The police seem certain (that) they will find the people responsible for the attack.We're not certain where they live.I'm not certain how much it will cost.It's not certain how much it will cost.I'm not certain who composed this symphony.It's not certain who composed this symphony.He was quite certain about the robber's identity.Can we be certain about/of the truth of what she said?If you are certain about someone, you have confidence in them and trust them.The new teacher hasn't been at the school for very long, and no one is quite certain about him yet.Before we offer him the job, we must make certain of his reliability.There is no certain (= known to be effective) solution to the problem.We shouldn't confuse rumours with certain (= known to be true) facts.One thing is certain (= known to be correct) - she won't resign willingly.I don't know for certain (= without any doubt) what I'll do when I leave school.
Cambridge English vocab. Кембриджский английский словарь. 2012