Belief (noun)

1. An acceptance that something is true or exists, especially one without proof.
2. Something one accepts as true or real.
3. A particular tenet or a body of tenets accepted by a group of persons.
4. Trust, faith, or confidence in someone or something.
5. The mental attitude that something is the case or true.

Origin:

Old english gebēlief "belief, trust", from gebēlīfan "to believe".

Examples:

1. He held a belief in the power of positive thinking.
2. The belief in god is central to their religion.
3. She had a strong belief in herself.
4. The belief in extraterrestrial life is a controversial topic.
5. The belief in the supernatural is a common human experience.