Chapter Ratihabition to Rattlings of R by Webster's Dictionary (1913 Edition)

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.

Rational
(Ra"tion*al), n. A rational being. Young.

Rationale
(Ra`tion*a"le) n. [L. rationalis, neut. rationale. See Rational, a.] An explanation or exposition of the principles of some opinion, action, hypothesis, phenomenon, or the like; also, the principles themselves.

Rationalism
(Ra"tion*al*ism) n. [Cf. F. rationalisme.]

1. (Theol.) The doctrine or system of those who deduce their religious opinions from reason or the understanding, as distinct from, or opposed to, revelation.

2. (Philos.) The system that makes rational power the ultimate test of truth; — opposed to sensualism, or sensationalism, and empiricism. Fleming.

Rationalist
(Ra"tion*al*ist), n. [Cf. F. rationaliste.] One who accepts rationalism as a theory or system; also, disparagingly, a false reasoner. See Citation under Reasonist.

Rationalistic
(Ra`tion*al*is"tic) Rationalistical
(Ra`tion*al*is"tic*al) a. Belonging to, or in accordance with, the principles of rationalism. — Ra`tion*al*is"tic*al*ly, adv.

Rationality
(Ra`tion*al"i*ty) n.; pl. -ties (- tiz). [F. rationalité, or L. rationalitas.] The quality or state of being rational; agreement with reason; possession of reason; due exercise of reason; reasonableness.

When God has made rationality the common portion of mankind, how came it to be thy inclosure?

Gov. of Tongue.

Well-directed intentions, whose rationalities will never bear a rigid examination.

Sir T. Browne.

Rationalization
(Ra`tion*al*i*za"tion) n. The act or process of rationalizing.