accreditation (n) granting approval or belief in a school
credential (n) a document that proves a person is believable
credible (adj) believable; reliable
credit (v) to believe that someone will do something
creditor (n) a person who believes that he will be paid back the money that he loaned
credulous (adj) tending to believe too easily; easily convinced; easily fooled
creed (n) a set of religious beliefs or principles
discredit (v) to refuse to believe; to reject as untrue
incredible (adj) not believable; improbable; unlikely
incredulous (adj) doubting; unwilling or unable to believe