An axiom is a proposition regarded as self-evidently true without proof. The word "axiom" is a slightly archaic synonym for postulate. Compare conjecture or hypothesis, both of which connote apparently true but not self-evident statements.

Archimedes' axiom | axiomatic system | axiom of choice | Cantor-Dedekind axiom | congruence axioms | conjecture | continuity axioms | countable additivity probability axiom | Dedekind's axiom | dimension axiom | Eilenberg-Steenrod axioms | excision axiom | Fano's axiom | field axioms | Hausdorff axioms | Hilbert's axioms | homotopy axiom | incidence axioms | independence axiom | induction axiom | law | lemma | long exact sequence of a pair axiom | ordering axioms | Pasch's axiom | Peano's axioms | Playfair's axiom | porism | postulate | probability axioms | Proclus' axiom | rule | T_2-separation axiom | theorem | Zermelo-Fraenkel axioms