- 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, relating to, or constituting reasoning powers: the rational faculty.
- proceeding or derived from reason or based on reasoning: a rational explanation.
- 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.
- Mathematics. rational number.
Origin of rational
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- using reason or logic in thinking out a problem
- in accordance with the principles of logic or reason; reasonable
- of sound mind; sanethe patient seemed quite rational
- endowed with the capacity to reason; capable of logical thoughtman is a rational being
- maths expressible as a ratio of two integers or polynomialsa rational number; a rational function
- maths a rational number
C14: from Latin ratiōnālis, from ratiō reason
Word Origin and History for ultra-rational
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).
Online Etymology Dictionary, © 2010 Douglas Harper
- 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.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.