belief

Etymology

From Middle English bileve, from Old English lēafa, from Proto-Germanic *laubō. Compare German Glaube (“faith, belief”). The replacement of final /v/ with /f/ is due to the analogy of noun-verb pairs with /f/ in the noun but /v/ in the verb, creating a pair belief : believe on the model of e.g. grief : grieve or proof : prove.

noun

1. Mental acceptance of a claim as true.
   It's my belief that the thief is somebody known to us.
   The belief that there is no conflict between [livestock] farming and arable production also seems to be unfounded: by preventing the growth of trees and other deep vegetation in the hills and by compacting the soil, grazing animals cause a cycle of flash floods and drought, sporadically drowning good land downstream and reducing the supply of irrigation water. 2013-12-06, George Monbiot, “Why I'm eating my words on veganism – again”, in The Guardian Weekly, volume 189, number 26, page 48
2. Faith or trust in the reality of something; often based upon one's own reasoning, trust in a claim, desire of actuality, and/or evidence considered.
   My belief is that there is a bear in the woods. Bill said he saw one.
   Based on this data, it is our belief that X does not occur.
3. (countable) Something believed.
   The ancient people have a belief in many deities.
4. (uncountable) The quality or state of believing.
   My belief that it will rain tomorrow is strong.
5. (uncountable) Religious faith.
   She often said it was her belief that carried her through the hard times.
6. (in the plural) One's religious or moral convictions.
   I can't do that. It's against my beliefs.