rational

[ rash-uh-nl, rash-nl ]
See synonyms for: rationalrationallyrationalness on Thesaurus.com

adjective
  1. agreeable to reason; reasonable; sensible: a rational plan for economic development.

  2. having or exercising reason, sound judgment, or good sense: a calm and rational negotiator.

  1. being in or characterized by full possession of one's reason; sane; lucid: The patient appeared perfectly rational.

  2. endowed with the faculty of reason: rational beings.

  3. of, relating to, or constituting reasoning powers: the rational faculty.

  4. proceeding or derived from reason or based on reasoning: a rational explanation.

  5. 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.

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

noun
  1. Mathematics. rational number.

Origin of rational

1
First recorded in 1350–1400; Middle English racional, from Latin ratiōnālis, equivalent to ratiōn- (stem of ratiō ) reason + -ālis -al1

synonym study For rational

6. See reasonable.

Other words for rational

Opposites for rational

Other words from rational

  • ra·tion·al·ly, adverb
  • ra·tion·al·ness, noun
  • an·ti·ra·tion·al, adjective
  • hy·per·ra·tion·al, adjective
  • non·ra·tion·al, adjective
  • o·ver·ra·tion·al, adjective
  • pre·ra·tion·al, adjective
  • qua·si-ra·tion·al, adjective
  • trans·ra·tion·al, adjective
  • ul·tra·ra·tion·al, adjective
  • un·ra·tion·al, adjective

Words that may be confused with rational

Words Nearby rational

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use rational in a sentence

British Dictionary definitions for rational

rational

/ (ˈræʃənəl) /


adjective
  1. using reason or logic in thinking out a problem

  2. in accordance with the principles of logic or reason; reasonable

  1. of sound mind; sane: the patient seemed quite rational

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

  3. maths expressible as a ratio of two integers or polynomials: a rational number; a rational function

noun
  1. maths a rational number

Origin of rational

1
C14: from Latin ratiōnālis, from ratiō reason

Derived forms of rational

  • rationally, adverb
  • rationalness, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012