Webster
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Webster’s Revised Unabridged Dictionary · 1913

Rational

Ra′tion·al (răsh′ŭn·al), a. [L. rationalis: cf. F. rationnel. See Ratio, Reason, and cf. Rationale.] 1. Relating to the reason; not physical; mental.

Moral philosophy was his chiefest end; for the rational, the natural, and mathematics . . . were but simple pastimes in comparison of the other. Sir T. North.

2. Having reason, or the faculty of reasoning; endowed with reason or understanding; reasoning.

It is our glory and happiness to have a rational nature. Law.

3. Agreeable to reason; not absurd, preposterous, extravagant, foolish, fanciful, or the like; wise; judicious; as, rational conduct; a rational man.

4. (Chem.) Expressing the type, structure, relations, and reactions of a compound; graphic; — said of formulæ. See under Formula.

Rational horizon. (Astron.) See Horizon, 2 (b). — Rational quantity (Alg.), one that can be expressed without the use of a radical sign, or in exact parts of unity; — opposed to irrational or radical quantity. — Rational symptom (Med.), one elicited by the statements of the patient himself and not as the result of a physical examination.

Syn. — Sane; sound; intelligent; reasonable; sensible; wise; discreet; judicious. — Rational, Reasonable. Rational has reference to reason as a faculty of the mind, and is opposed to irrational; as, a rational being, a rational state of mind, rational views, etc. In these cases the speculative reason is more particularly referred to. Reasonable has reference to the exercise of this faculty for practical purposes, and means, governed or directed by reason; as, reasonable desires or plans; a reasonable charge; a reasonable prospect of success.

What higher in her society thou find'st Attractive, human, rational, love still. Milton.

A law may be reasonable in itself, although a man does not allow it, or does not know the reason of the lawgivers. Swift.

Ra′tion·al, n. A rational being. Young.

Webster’s Revised Unabridged Dictionary, Noah Porter, editor (Springfield, Mass.: G. & C. Merriam, 1913). Public domain. Text as transcribed by MICRA, Inc., from Project Gutenberg. Changed for Deep Dive Bible: Greek, which our source spelled in Latin letters, set in Greek letters; entries of one spelling merged into one article; Greek words our source left out (shown as “?”), read from the 1898 printing, from the same plates (the Library of Congress’s copy), where the place could be found with certainty. Of the others, 1,362 (a word or a single letter each) were inferred by AI from the context by the dictionary’s own rules and are marked with a wavy underline (tap or point at one to see the note); the rest, which could not be inferred with confidence, are left as “?”.