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.
Still, pointing at newly rising roster-compensation costs will serve as the rationale as to why this is happening now. Jason Kirk, New York Times, 31 July 2026 Cameron lobbied to pitch the ninth inning but understood his manager’s rationale. Kansas City Star, 30 July 2026 In the end, flexible architecture for the people could only come to fruition by undercutting its own populist rationale. Justin Davidson, Curbed, 29 July 2026 Failure to report use of force Green explained her rationale in the personnel board’s order, giving a glimpse into what the video footage showed. Corey Schmidt, Sacbee.com, 29 July 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 5 Aug. 2026.

Kids Definition

rationale

noun
: a basic reason or explanation for something

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