axiom
n.a rule or statement that everyone accepts as true without needing proof. It is the starting point for a bigger idea or a system of math.
n.a self-evident truth that requires no proof to be accepted; a starting proposition in a logical system from which other truths are derived.
“It is a mathematical axiom that the whole is greater than the part.”
“The entire legal argument was built upon the axiom that all citizens deserve equal protection under the law.”
“In Euclidean geometry, the parallel postulate was long considered an unshakeable axiom until the development of non-Euclidean systems challenged its universal necessity.”
Often used in formal logic, mathematics, and philosophy to describe foundational principles.
From Middle French axiome in the 15th century, from Latin axiōma (“axiom; principle”), from Ancient Greek ἀξίωμα (axíōma, “that which is thought to fit, a requisite, that which a pupil is required to know beforehand, a self-evident principle”), from ἀξιόω (axióō, “to think fit or worthy, to require, to demand”), from ἄξιος (áxios, “fit, worthy”, literally “weighing as much as; of like value”), from ἄγω (ágō, “to weigh (down)”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.