belief

What it means

1. countableuncountableMental acceptance of a claim as true.

   It's my belief that the thief is somebody known to us.

   1 more example

   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 December 6, George Monbiot, “Why I'm eating my words on veganism – again”, in The Guardian Weekly, volume 189, number 26, page 48

2. countableuncountableFaith 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.

   Based on this data, it is our belief that X does not occur.

   1 more example

   My belief is that there is a bear in the woods. Bill said he saw one.

3. countableSomething believed.

   The ancient people have a belief in many deities.

In a sentence

It's my belief that the thief is somebody known to us.

Where it comes from

1. Proto-Indo-European*lewbʰ-
2. Proto-Germanic*laubō
3. Proto-West Germanic*laubu
4. Old Englishlēafa
5. Middle Englishbileve
6. Englishbelief

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 /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.