casus belli

noun

ca·​sus bel·​li ˈkä-səs-ˈbe-ˌlē How to pronounce casus belli (audio) ˈkā-səs-ˈbe-ˌlī How to pronounce casus belli (audio)
plural casus belli
: an event or action that justifies or allegedly justifies a war or conflict

Examples of casus belli in a Sentence

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.
This is not the case of the missing casus belli. — Isaac Chotiner, New Yorker, 28 Feb. 2026 But what Putin can live with today may become a casus belli tomorrow. — George Beebe, TIME, 1 July 2024 Why hand the Americans a casus belli if coercion might work first? — Micah McCartney, MSNBC Newsweek, 1 Apr. 2026 The initial deal is to be followed by talks on the war’s supposed casus belli, Iran’s nuclear program. — Arash Azizi, The Atlantic, 27 May 2026 See All Example Sentences for casus belli

Word History

Etymology

New Latin, occasion of war

First Known Use

circa 1841, in the meaning defined above

Time Traveler
The first known use of casus belli was circa 1841

Rhymes for casus belli

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Browse Nearby Words

casula
casus belli
casus foederis
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Cite this Entry

“Casus belli.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/casus%20belli. Accessed 8 Jul. 2026.

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