Rational

(rāsh'un-al), a. [Lat. rationalis, It. razionale, Sp., Pg., & Pr. racional, Fr. rationnel. See RATIO.]

1. Relating to the reason; not physical. Milton.
2. Having reason, or the faculty of reasoning; endowed with reason;—opposed to irrational; as, man is a rational being; brutes are not rational animals.

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. Rational horizon. See HORIZON, 2, (b).—Rational quantity (Alg.), a quantity that can be expressed without the use of a radical sign, or in exact parts of unity;—opposed to irrational or radical quantity. 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, &c. In these cases, the speculative reason is more particularly referred to. Reasonable has reference to the exercise of this faculty for practical purposes, and denotes governed or directed by reason; as, reasonable desires, plans, &c.; a reasonable charge; a reasonable prospect of success. What higher in her society than find'st Attractive, humane, 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.

(rāsh'un-al), n. A rational being. Young. Rā'tion-ā'le (rāsh'un-ā'le) (Synop., § 130), n. [Fr. rational, Sp. racional, from Lat. rationalis. See RATIONAL.]

1. A detail with reasons; a series of reasons assigned; as, Dr. Sparrow's Rationale of the Common Prayer.
2. An explanation of the principles of some opinion, action, hypothesis, phenomenon, and the like, or the principles themselves.