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rational

Etymology and origin of the English word rational

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Confidence
Established
Formation
Borrowing
First attested
before 1398
Borrowed from
Old French racionel via Middle English
Ultimate origin
Latin (rationalis)

Pronunciation

  • IPA: /ˈɹæʃ(ə)nəl/[1]

Etymology

It is inherited from Middle English racional, borrowed from Old French racionel and directly from Latin ratiōnālis, of or belonging to reason, reasonable,[2][3] from ratiō, ratiōnis, reckoning, calculation, reason (see ratio, reason),[2][3][4] from rat-, past participle stem of rērī, to reckon, think.[2]

Earliest recorded meaning

Having the faculty of reasoning: before 1398, in Trevisa's translation of Bartholomaeus;[2][5] Etymonline dates the sense pertaining to reason to the late 14th century and of persons to the mid-15th.[3]

Semantic evolution

Based on or derived from reason is from 1531,[5] and in arithmetic, expressible in finite terms, from the 1560s.[3] Exercising one's reason properly, sensible, is from 1632.[5] Hoad dates the sense agreeable to reason, reasonable, to the 17th century.[6] An ancient class of physicians who reasoned from theory are rational from 1541,[5] and Rational Christians from 1750.[5]

Timeline

  • before 1398 – endowed with reason.[2]
  • 1531 – based on reason.[5]
  • 1541 – rational physicians.[5]
  • 1560s – in arithmetic.[3]
  • 1632 – sensible.[5]

Modern meaning

Adjective

  1. Having or using the ability to reason.
  2. Consistent with or based on reason; logical.
  3. Of sound mind; sane.
  4. (mathematics) Expressible as a ratio of two integers.

Word family

  • rationally
  • rationalness
  • rationalization
  • antirational
  • hyperrational
  • nonrational
  • overrational
  • prerational
  • irrational
  • rationale
  • rationality
  • subrational
  • suprarational
  • reason
  • ratio
  • ration
  • rationalize

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  3. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ Pearsall, Judy, ed. (1998), The New Oxford Dictionary of English, Oxford: Clarendon Press
  5. ^ a b c d e f g h Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
  6. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press

Related etymologies

Cite this entry

“Rational.” Etymologically, 17 Oct. 2026, etymologically.com/en/rational. Accessed 17 Oct. 2026.

Last edited on . ·