1 [never before noun] having no doubts that something is true
I’m not absolutely certain, but I think I’m right.
certain (that): You can be pretty certain she’s not going to like it.
certain who: We still can’t be certain who is going to win.
certain of/about: I’ve never been more certain of anything in my entire life.
You don’t seem too certain about it.
know/say for certain: I think I met her in 1985, but I can’t say for certain.
Synonyms and related words