(transitive) to believe (someone) / to believe, to accept as true [+ à (something)] / to believe, to have faith [+ en (object) = in] / (reflexive, often followed by an adjective) to think of oneself as, to consider oneself as

if (someone) were to be believed, according to (someone)

(transitive) to take someone's word for it, to take someone at their word

to suggest (to someone) that; to lead someone to believe that, to make someone think that

(simile, informal) to firmly believe in, to be firmly convinced of [+ à (something)]

(informal) not to believe one's ears

(informal) not to believe one's eyes

not to know how right one is (said when someone who has uttered a statement doesn't know that this statement is even truer than they thought, for example because there is another dimension to it that they weren't aware of)

(rare, figuratively, derogatory) to think one is God's gift to the world, to think one is the business, to be full of oneself

seeing is believing