—adj.
1 a (often foll. by of, or that + clause) confident, convinced (certain that I put it here). b (often foll. by that + clause) indisputable; known for sure (it is certain that he is guilty).
2 (often foll. by to + infin.) a that may be relied on to happen (it is certain to rain). b destined (certain to become a star).
3 definite, unfailing, reliable (a certain indication of the coming storm; his touch is certain).
4 (of a person, place, etc.) that might be specified, but is not (a certain lady; of a certain age).
5 some though not much (a certain reluctance).
6 (of a person, place, etc.) existing, though probably unknown to the reader or hearer (a certain John Smith).
—pron. (as pl.) some but not all (certain of them were wounded).
Phrases and idioms:
for certain without doubt. make certain = make sure (see SURE).
Etymology: ME f. OF ult. f. L certus settled
Useful english dictionary. 2012.