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

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If someone asserts that the word rationale refers to a ration of ale, they are wrong, but that doesn’t mean they don’t have an actual rationale (a reason, explanation, or basis) for such a claim. “Rationale looks like the words ration and ale jammed together,” they could offer, and while that is true you’d be justified in responding: “Appearances can be deceiving.” Rationale is a direct borrowing of the Latin word rationale, with which it shares the meaning “an explanation of controlling principles of opinion, belief, practice, or phenomena.” The Latin rationale comes from a form of the adjective rationalis (“rational”), which traces back to the noun ratio, meaning “reason.” While the Latin ratio is also the forebear of the English noun ration, referring to a share of something, rationale has nothing to do with a tankard (or stein, or even a pony) of beer.

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The rationale was simple—winning the race to build these weapons would enable the US and its allies to achieve victory in World War II, hasten an end to the fighting, and ultimately save lives. Michael Posner, Forbes.com, 7 Aug. 2026 Precinct 2 Commissioner Alisa Simmons later pressed Ludwig on his rationale for cutting the number of sites. Rachel Royster, Fort Worth Star-Telegram, 5 Aug. 2026 Maintaining two parallel education systems for functionally equivalent degrees has outgrown its rationale. Abigail MacKenzie, STAT, 5 Aug. 2026 The filing points to exemptions the states say undermine the administration's rationale. Luke Fountain, CNBC, 3 Aug. 2026 See All Example Sentences for rationale

Word History

Etymology

Latin, neuter of rationalis

First Known Use

1657, in the meaning defined at sense 1

Time Traveler
The first known use of rationale was in 1657

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Cite this Entry

“Rationale.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rationale. Accessed 16 Aug. 2026.

Kids Definition

rationale

noun
: a basic reason or explanation for something

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