Other forms: believes, beliefs
A belief is something you hold to be true. A firm belief, religious beliefs, contrary to popular belief.
The plural is common for religious or political convictions: his beliefs, freedom of belief. The uncountable use means trust or confidence: belief in her, a loss of belief. Beyond belief means impossible to accept, and beggars belief is the stronger form of the same. Note that belief is the noun and believe the verb — the spelling changes with the part of speech, which is a common source of error.
1nounbeliefSomething held to be true.
“It was a firm belief and there was no evidence for it at all.”
2nountrustTrust or confidence in somebody or something.
“His belief in the project outlasted everybody else's.”
belief is something held true.
Old English geleafa is built from the root that also gives leave, love and lief — the idea of holding something dear. To believe was to hold dear before it was to hold true, which is a sharper account of belief than most.
Middle English
bileve
English, today
belief
From Middle English bileve. From Middle English bileve, from Old English lēafa, from Proto-West Germanic laubu from Proto-Germanic laubō. Compare German Glaube (“faith, belief”). The replacement of final with is due to the analogy of noun-verb pairs with in the noun but in the verb, creating a pair belief: believe on the model of e.g. grief: grieve or proof: prove.
Etymology from Wiktionary, CC BY-SA