*axiom*

n. [ L. axioma, Gr. &unr_; that which is thought worthy, that which is assumed, a basis of demonstration, a principle, fr. &unr_; to think worthy, fr. &unr_; worthy, weighing as much as; cf. &unr_; to lead, drive, also to weigh so much: cf F. axiome. See Agent, a. ] 1. (Logic & Math.) A self-evident and necessary truth, or a proposition whose truth is so evident as first sight that no reasoning or demonstration can make it plainer; a proposition which it is necessary to take for granted; as, “The whole is greater than a part;” “A thing can not, at the same time, be and not be.” [ 1913 Webster ]

2. An established principle in some art or science, which, though not a necessary truth, is universally received; as, the axioms of political economy. [ 1913 Webster ]

Syn. -- Axiom, Maxim, Aphorism, Adage. An axiom is a self-evident truth which is taken for granted as the basis of reasoning. A maxim is a guiding principle sanctioned by experience, and relating especially to the practical concerns of life. An aphorism is a short sentence pithily expressing some valuable and general truth or sentiment. An adage is a saying of long-established authority and of universal application. [ 1913 Webster ]