ra·​tio·​nale | \ˌra-shə-ˈnal \

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

His administration has used this rationale to deploy thousands of active-duty military to the border in California, Arizona, and Texas to support border agents. Tara Golshan, Vox, "What Trump’s “lethal force” authorization means at the border," 27 Nov. 2018 That's no shade to Alessia or Chance, but a comment on the ever-fluctuating rationales of award shows. Allie Gemmill, Teen Vogue, "BTS Is Ineligible for a Best New Artist Grammy and Fans Have Jokes," 2 Nov. 2018 Disclose in advance the evidence used to draft a local coverage determination so the public can review and respond to the rationale. Scott Whitaker, STAT, "It’s time to reform the process for determining what Medicare covers," 27 June 2018 There’s no indisputable scientific rationale for why some of these (lucky) women eventually detached from the pain points of childbirth and the postpartum period after, though there are theories. Jessica Delfino, SELF, "Do Women Really 'Forget' the Pain of Childbirth? Because I Sure Didn’t," 13 Nov. 2018 Reflecting on these questions will help to establish a rationale behind your decision to protest. Amnesty International Usa, Teen Vogue, "How to Legally Protest as a Public School Student," 12 Oct. 2018 For the last few seasons Joseph, formerly a runway regular at London Fashion Week, had faded from the schedule into the painful purgatory of showroom presentations—and with no satisfactory rationale to explain the decline. Luke Leitch, Vogue, "Lacoste Appoints Louise Trotter as Creative Director," 4 Oct. 2018 That’s part of the rationale behind Pepsi’s $3.2 billion purchase of refillable seltzer water maker SodaStream. Rani Molla, Recode, "SodaStream’s path to its $3.2 billion Pepsi deal," 20 Aug. 2018 Experts who’ve studied trauma fees say that at some hospitals there’s little rationale behind how hospitals calculate the charge and when the fee is billed. Jenny Gold, Kaiser Health News And Sarah Kliff, Washington Post, "A Baby Was Treated With A Nap And A Bottle Of Formula. The Bill Was $18,000.," 2 July 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

6 Dec 2018

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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

: the reason or explanation for something


ra·​tio·​nale | \ˌra-shə-ˈnal \

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 make faulty or ineffective

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