(idiomatic) An emphatic form of believe me: you (the subject) had better believe me (the speaker).

(intransitive, chiefly UK) To appear implausible or unbelievable.

Alternative spelling of true-believer syndrome

A phenomenon in which witnesses to a staged event continue to believe in its authenticity even after it has been debunked.

(transitive) To ascribe existence to. / (transitive) To believe that (something) is right or desirable. / (transitive) To have confidence in the ability or power of.

simple past tense and past participle of believe in

Third-person singular simple present indicative form of believe in

present participle of believe in

alternative spelling of nonbeliever

(Britain, Ireland, sarcastic) Used to indicate that the speaker does not put faith in something they have just heard.