certain adj.
VERBS be, feel, look, seem Digby looked certain to be the next president. | become, grow I grew more and more certain that she was lying to me. | make Make certain that you lock the door if you go out.
ADV. very | absolutely, quite | by no means It's by no means certain that she'll get the job. | almost | fairly, pretty
PREP. about/of Are you quite certain about this?
PHRASES can't/couldn't say for certain I think she's a teacher, but I couldn't say for certain. | not know for certain I don't know for certain how many people are coming.
You can also check other dicts: certain (English, 中文解释 ), wordnet sense, Collins Definition