Two registers: in math/logic,
公理 is the precise term for 'axiom' (an unproven starting principle, e.g.
平行公理 'parallel postulate'). In everyday speech,
公理 means 'common-sense truth / universally accepted right' - often paired with
公道 (gōngdào, 'justice'). Distinguish from
定理 (dìnglǐ, 'theorem' - something proven from axioms).
