having good reasons to believe something; free from doubt; proved; reliable; without a doubt
certain, definite
Cases of word usage
1) to feel sure of the truth of (something, that a person is honest etc) (believe)
2) something that is certain, easy or sure (cinch)
3) too confident or sure of one's ability etc (cocky)
4) to make sure (that) something will happen (ensure)
5) (of the body) having little power or energy; (of the mind) not confident, sure or determined; easily broken, damaged etc; easily defeated or changed (weak)
