ra·​tio·​nale | \ ˌra-shə-ˈnal How to pronounce rationale (audio) \

Definition of rationale

1 : an explanation of controlling principles of opinion, belief, practice, or phenomena
2 : an underlying reason : basis

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Did You Know?

The word rationale appeared in the second half of the 17th century, just in time for the Age of Reason. It is based on the Latin ratio, which means "reason," and rationalis, which means "endowed with reason." At first, rationale meant "an explanation of controlling principles" ("a rationale of religious practices," for example), but soon it began to refer to the underlying reason for something (as in "the rationale for her behavior"). The latter meaning is now the most common use of the term. The English word ratio can also mean "underlying reason" (in fact, it had this meaning before rationale did), but in current use, that word more often refers to the relationship (in number, quantity, or degree) between things.

Examples of rationale in a Sentence

the rationale for starting the school day an hour later is that kids will supposedly get an extra hour of sleep

Recent Examples on the Web

The one thing that Commerce Secretary Wilbur Ross didn’t have the right to do, however, was make up a phony reason for his decision and try to palm that off on the courts as the true rationale, Roberts wrote. David Lauter, latimes.com, "As Trump retreats on census, outlines of next battle come into focus," 12 July 2019 Most of the seven justices in the majority offered unique but overlapping rationales. Nr Editors, National Review, "The Week," 11 July 2019 The Labor Department has provided reporters with statements from an FBI agent and career prosecutor at the time that corroborate this rationale. Anna North, Vox, "Labor Secretary Alexander Acosta has no good answer for cushy Jeffrey Epstein plea deal," 10 July 2019 According to Roberts, Ross’s rationale—that the Justice Department needed citizenship data from the Census Bureau to better enforce the Voting Rights Act of 1965—was phony. Cristian Farias, The New Yorker, "The Battle Over the Census Citizenship Question Is Now About Civil Rights," 8 July 2019 Critics called that rationale a pretext for partisan motives. Reuters, The Mercury News, "Trump’s comments sow ‘confusion’ over census question," 3 July 2019 The motive or rationale from the suspect, that’s a million-dollar question. Fox News, "California deputy shot while getting food at Jack in the Box has died, officials say," 13 June 2019 On March 29th James Murdoch, Fox’s boss, reiterated this rationale at Code, a media conference in California. The Economist, "Comcast and Disney battle over Rupert Murdoch’s empire," 31 May 2018 In his public comments on the tariffs, however, the president rarely references this rationale, focusing instead on an economic argument for taking radical measures to reduce America’s trade deficit. Eric Levitz, Daily Intelligencer, "Trump Slaps Steel and Aluminum Tariffs on the E.U., Canada, and Mexico," 31 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rationale.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of rationale

1657, in the meaning defined at sense 1

History and Etymology for rationale

Latin, neuter of rationalis

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Statistics for rationale

Last Updated

19 Jul 2019

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Time Traveler for rationale

The first known use of rationale was in 1657

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English Language Learners Definition of rationale

somewhat formal : the reason or explanation for something


ra·​tio·​nale | \ ˌra-shə-ˈnal How to pronounce rationale (audio) \

Kids Definition of rationale

: a basic explanation or reason for something What is the rationale behind your decision?

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Comments on rationale

What made you want to look up rationale? Please tell us where you read or heard it (including the quote, if possible).


to complain fretfully

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