Axiom
AX'IOM, noun [Gr. authority, an authoritative sentence, or that which is assumed, from worthy, and to think worthy, to esteem; Eng. to ask, that which is asked, sought or esteemed.]
1. A self evident truth, or a proposition whose truth is so evident at first sight, that no process of reasoning or demonstration can make it plainer; as, 'the whole is greater than a part.'
2. An established principle in some art or science; a principle received without new proof; as, 'things which are equal to the same thing, are equal to one another.'