rational

[rash-uh-nl, rash-nl] /ˈræʃ ə nl, ˈræʃ nl/

adjective

agreeable to reason; reasonable; sensible:

a rational plan for economic development.

having or exercising reason, sound judgment, or good sense:

a calm and rational negotiator.

being in or characterized by full possession of one's reason; sane; lucid:

The patient appeared perfectly rational.

endowed with the faculty of reason:

rational beings.

of, pertaining to, or constituting reasoning powers:

the rational faculty.

proceeding or derived from reason or based on reasoning:

a rational explanation.

Mathematics.

capable of being expressed exactly by a ratio of two integers.
(of a function) capable of being expressed exactly by a ratio of two polynomials.

Classical Prosody. capable of measurement in terms of the metrical unit or mora.

noun

Mathematics, rational number.

Origin

1350-1400; Middle English racional < Latin ratiōnālis, equivalent to ratiōn- (stem of ratiō) reason + -ālis -al¹

Related forms

rationally, adverb

rationalness, noun

antirational, adjective

antirationally, adverb

hyperrational, adjective

hyperrationally, adverb

nonrational, adjective

nonrationally, adverb

overrational, adjective

overrationally, adverb

prerational, adjective

quasi-rational, adjective

quasi-rationally, adverb

transrational, adjective

transrationally, adverb

ultrarational, adjective

ultrarationally, adverb

unrational, adjective

unrationally, adverb

Can be confused

rational, reasonable (see synonym study at reasonable)

Synonyms

2. intelligent, wise, judicious, sagacious, enlightened. 6. See reasonable.

Antonyms

2. stupid. 3. insane.

Examples from the web for rational

The discussion is interesting, because today our superficial rational mind finds its limits and believes in the human ego alone.
Well thank goodness the fossil fuel industry is based on sound economics and rational politics.
The important is being rational, realist and thruer guesses, imaginations.
To attempt to steer a rational middle course between these extremes, however, demands for its success some rehearsal of the facts.
But optimal learning demands a kind of rational control over ourselves that does not come easily.
Much of people's behavior in elevators is not the result of rational thinking.
Well-informed consumers tend to make rational decisions.
And those people go out looking for reasons, something rational to explain an irrational process.
From an economic-utility point of view, our students are making completely rational decisions.
So rational busy people should measure time more accurately, and manage it more efficiently.

British Dictionary definitions for rational

rational

/ˈræʃənəl/

adjective

using reason or logic in thinking out a problem

in accordance with the principles of logic or reason; reasonable

of sound mind; sane: the patient seemed quite rational

endowed with the capacity to reason; capable of logical thought: man is a rational being

(maths) expressible as a ratio of two integers or polynomials: a rational number; a rational function

noun

(maths) a rational number

Derived Forms

rationally, adverb
rationalness, noun

Word Origin

C14: from Latin ratiōnālis, from ratiōreason

Word Origin and History for rational

adj.

late 14c., "pertaining to reason;" mid-15c., "endowed with reason," from Old French racionel and directly from Latin rationalis "of or belonging to reason, reasonable," from ratio (genitive rationis) "reckoning, calculation, reason" (see ratio).

rational in Medicine

rational ra·tion·al (rāsh'ə-nəl)
adj.

Having or exercising the ability to reason.
Influenced by reasoning rather than by emotion.
Of sound mind; sane.
Based on scientific knowledge or theory rather than practical observation.

rational in Technology

[Mathematics] a fractional number n/d, where n and d are integers, n is the numerator and d is the denominator. The set of all rational numbers is usually called Q. Computers do not usually deal with rational numbers but instead convert them to real numbers which are represented (approximately in some cases) as floating-point numbers. Compare irrational.