Verity (noun)

A true principle or belief, especially one of fundamental importance.

Origin:

Late middle english: from old french verite, from latin veritas, from verus "true". .

Examples:

1. Freedom of speech is a verity of democratic societies.
2. The verity of the statement was proven by the facts.
3. It is a verity that all people are equal under the law.
4. The verity of the theory has been supported by extensive research.
5. The verity of the statement was undeniable.