Answer: postulate
Explanation:
An axiom or postulate is a statement that is always taken to be true, to use as a premise or beginning point for reasoning and arguments.
An axiom is taken to be true without proof whereas postulate are the basic structure from that theorems and lemmas are derived.
A postulate is assumed to be a fact and used to derive conclusions about any argument .
Therefore, An axiom or a postulate is an accepted statement of fact.