noun a rational being.
2. rational ·adj relating to the reason; not physical; mental.
3. rational ·adj having reason, or the faculty of reasoning; endowed with reason or understanding; reasoning.
4. rational ·adj expressing the type, structure, relations, and reactions of a compound; graphic;
said of formulae. ·see under formula.
5. rational ·adj agreeable to reason; not absurd, preposterous, extravagant, foolish, fanciful, or the like; wise; judicious; as, rational conduct; a rational man.