(logic) a proposition that is not susceptible of proof or disproof; its truth is assumed to be self-evident
"The team decided to treat the law of non-contradiction as an axiom, accepting its truth without needing further proof."
A seemingly self-evident or necessary truth which is based on assumption; a principle or proposition which cannot actually be proved or disproved.
"The team's entire project strategy relied on the axiom that customers would prioritize speed over cost, even though no data supported that belief."