rationale

Etymology

It is borrowed from Medieval Latin ratiōnāle (“a reasoned exposition”), used in the titles of works from the 12th century, as in the “Rationale divinorum officiorum”,^[2] the noun use of the neuter of Latin ratiōnālis (“of or belonging to reason, rational”),^[2][3][4][5] from ratiō (“reckoning, reason”).^[3][6] Etymonline, Barnhart and the American Heritage Dictionary call the source Late Latin,^[3][4][7] and the Shorter Oxford, the Oxford Dictionary of English and Collins modern Latin.^[8][9][10] It is related to rational.^[3][7]

Earliest recorded meaning

A reasoned exposition of principles, or a statement of reasons: 1580, in T. N.'s translation of P. Mexía's Pleasaunt Dialogue.^[2][11] Barnhart and Etymonline date the word to 1657 and the 1650s.^[4][3]

Semantic evolution

The sense "the fundamental reason for something, its rational basis" is quoted from 1651, in Jeremy Taylor's Clerus Domini,^[2] while Barnhart and Etymonline date it to 1688 and the 1680s.^[4][3] The word was long used in book titles: Johnson (1755) defined it as "a detail with reasons", citing Sparrow's Rationale of the Common Prayer.^[6] The OED also notes the meaning of an attempted justification for something.^[2]

Timeline

• 1580 – a reasoned exposition of principles.^[2][11]
• 1651 – the fundamental reason for something.^[2]
• 1657 – date given by Barnhart.^[4]
• 1755 – Johnson: a detail with reasons.^[6]

Meanings

Noun

1. The underlying reasons or principles behind a decision, belief or course of action: The memo set out the rationale for closing the branch.^[11][10][2]
2. A reasoned exposition of principles; an explanation, or an attempted justification.^[2][10][8]

Related words

• rational
• ratio
• reason
• ration

Usage notes

The pronunciation has changed.^[2][12] The first edition of the OED (1903) gave /ræʃəˈneɪliː/, with the final -e sounded, as other dictionaries did until the early 20th century;^[2] Daniel Jones (from 1917) and Webster's (1934) gave /ɑː/ with the -e still sounded.^[2] Fowler (1926) noted a pronunciation with a silent -e, which he put down to confusion with French-looking words such as morale and locale, and it has been recorded by dictionaries since the mid-20th century.^[2] Today it is /ˌræʃ.əˈnɑːl/ or /-ˈnæl/, less often /-ˈnɑː.leɪ/, in Britain and /ˌræʃ.əˈnæl/ in the United States.^[12] The OED also records rationale for the breastplate of the Jewish high priest (Old English to 1852), after Ancient Greek λογεῖον (logeîon), and for a bishop's breast ornament (from 1849).^[2]

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b c Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
7. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
8. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
9. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
10. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins
11. ^ a b c Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
12. ^ a b Jones, Daniel (2011), Cambridge English Pronouncing Dictionary, 18th ed., ed. Peter Roach, Jane Setter and John Esling, Cambridge: Cambridge University Press