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

Their rationale: Anything added should have a practical purpose. Sienna Fantozzi, House Beautiful, "Everything You Need To Know About Scandinavian Design," 18 Sep. 2018 His work arrived in Germany at the height of the völkisch movement, which romanticized German ethno-cultural heritage and hailed his writings as scientific rationales for racial cleansing. Ruth Margalit, The New Yorker, "The Mail," 11 May 2018 Those rationales are still used today despite the abundant evidence, most recently from the Obama administration’s stimulus program, of how ineffective such federal spending is. John Tierney, National Review, "Trump’s Infrastructure Opportunity," 25 Jan. 2018 Feeling tired is a reason to exercise, not a rationale for skipping it. Gretchen Rubin, Good Housekeeping, "The Happiness Project: Stress Less," 3 May 2013 Among the appointments are a top former military commander, Mohammed Fazl, who is expected to prove popular among the Taliban rank-and-file and boost the office’s negotiating clout, people familiar with the rationale for the step say. Saeed Shah, WSJ, "U.S. Faces Newly Muscular Taliban in Peace-Talk Efforts," 5 Nov. 2018 The video's end seems to align with that rationale. Sam Blum, Popular Mechanics, "Here's a Look Inside Banksy's $1.4 Million Paper Shredder," 18 Oct. 2018 In succeeding decades, Supreme Court opinions built on that rationale to significantly limit privacy rights for drivers and passengers. Jess Bravin, WSJ, "Police Need Warrants to Search Vehicles at Private Homes, High Court Rules," 29 May 2018 The California secretary of state's office approved her ballot designation based on that rationale. Emily Cadei, sacbee, "Democratic congressional candidate's ad could lead to false impressions | The Sacramento Bee," 15 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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Last Updated

24 May 2019

Look-up Popularity

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).


a strong desire or propensity

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