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

Did you know?

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.
But evidence from other shootings involving immigration enforcement officers has sometimes called into question that rationale. — Rebecca Santana, Los Angeles Times, 9 Oct. 2026 With American troops no longer based in Irbil, that rationale has expired. — Firmesk Rahim, The Conversation, 9 Oct. 2026 While the Fed’s policymakers voted unanimously to raise interest rates last month, they were divided over the rationale for doing so. — Brendan Ruberry, semafor.com, 7 Oct. 2026 That means documenting rationale, reviewing important patterns against real user behavior and giving teams a clear path to propose changes when the evidence changes. — Goran Paun, Forbes.com, 6 Oct. 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

Browse Nearby Words

Podcast

Cite this Entry

“Rationale.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rationale. Accessed 14 Oct. 2026.

Kids Definition

rationale

noun
: a basic reason or explanation for something
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!