rational

English Online Dictionary. What means rational‎? What does rational mean?

English

Alternative forms

• rationall (obsolete)

Pronunciation

• enPR: ră'sh(ə)nəl, IPA^(key): /ˈɹæʃ(ə)nəl/
• Rhymes: -æʃənəl

Etymology 1

From Old French rationel, rational, from Latin rationalis (“of or belonging to reason, rational, reasonable; having a ratio”), from ratio (“reason; calculation”).

Adjective

rational (comparative more rational, superlative most rational)

1. Capable of reasoning.
2. Logically sound; not self-contradictory or otherwise absurd.
   • 1812 The Freethinking Christians' Magazine: Volume 2 p. 21

     Prevention for the future is now almost universally allowed to be the only rational plea for the infliction of punishment; but this, when left to the arbitrary discretion of individuals, always has been found, and always will be found, to degenerate into the exercise of revenge for the past.

3. (of a person or personal characteristics) Healthy or balanced intellectually; exhibiting reasonableness.
   • 1867 C. Handfield Jones, Case Of Low Fever: Delirium: Incomplete Dementia. The British Medical Journal Vol. 2, No. 344, Aug. 3

     Temperature 99.8 degrees. Pulse 104. She was quite conscious and rational at times, at others very noisy.
4. (mathematics, not comparable) Comprising, or expressible as, a ratio
   1. (arithmetic) Of a number, capable of being expressed as the ratio of two integers.

      ¾ is a rational number, but √2 is an irrational number.

   2. (algebra) Of an algebraic expression in indeterminates, or more generally a function: capable of being expressed as the ratio of two polynomials.
   3. (algebraic geometry) Of a variety: (informally) geometrically simple almost everywhere; (formally) birationally equivalent to projective space
   4. (algebraic geometry) Of a function between varieties: acting as a morphism on an open subset of its domain.
   5. (algebraic geometry) Of a point on an algebraic variety over a field: whose coordinates belong to the field in question (in contrast to those points of the variety which are only defined over the algebraic closure of the base field).
5. (chemistry) Expressing the type, structure, relations, and reactions of a compound; graphic; said of formulae.
6. (physics) Expressing a physical object.

Antonyms

• (antonym(s) of “reasonable”): absurd, irrational, nonsensical, arbitrary
• (antonym(s) of “capable of reasoning”): arational, irrational, non-rational
• (antonym(s) of “number theory”): irrational

Derived terms

Related terms

Translations

Noun

rational (plural rationals)

1. (mathematics) A rational number: a number that can be expressed as the quotient of two integers.

Translations

Etymology 2

From Old French rational, from Medieval Latin rationale (“a pontifical stole, a pallium, an ornament worn over the chasuble”), neuter of Latin rationalis (“rational”), for which see the first etymology. Translation of λογεῖον (logeîon) or perhaps λόγιον (lógion, “oracle”) in the Septuagint version of Exodus 28.

Noun

rational (plural rationals)

1. (historical) The breastplate worn by Israelite high priests.

Translations

References

• “rational”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• “rational”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.

Further reading

• "rational" in Raymond Williams, Keywords (revised), 1983, Fontana Press, page 252.

Anagrams

• notarial

French

Pronunciation

Noun

rational f (plural rationaux)

1. rationale (religious clothing)

Further reading

• “rational”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012.

German

Etymology

Borrowed from Latin rationalis.

Pronunciation

• IPA^(key): [ˌʁat͡si̯oˈnaːl]
• Hyphenation: ra‧ti‧o‧nal

Adjective

rational (strong nominative masculine singular rationaler, comparative rationaler, superlative am rationalsten)

1. rational

Declension

Further reading

• “rational” in Duden online
• “rational” in Digitales Wörterbuch der deutschen Sprache