[A_perfect_lady]

The actual definition of belief is "the acceptance" that something is true. That is, if someone else says they know, and you accept that (without knowing yourself), that is belief. To hold something to be true despite having no evidence, that is belief.

In fact, I'd suggest a hierarchy as follows.

know: hold something to be true based on experience or established facts
theorize: to hold something to be true based on principles
hypothesize: to hold something to be true based on limited evidence
believe: to hold something to be true independent of evidence

[IronJack]

believe: to hold something to be true independent of evidence

Faith: the belief in things unseen.