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Definitions

casus belli

[key-suhs bel-ahy, bel-ee, kah-soos bel-lee] / ˈkeɪ səs ˈbɛl aɪ, ˈbɛl i, ˈkɑ sʊs ˈbɛl li /


NOUN
root of the matter
Synonyms


Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

In his speech announcing the war, Mr. Trump explained the extensive casus belli to the American people.

From The Wall Street Journal • Mar. 2, 2026

Rather, this narrow goal may be intended to serve as an official casus belli, giving Russian diplomats something to cite, however implausible, particularly at the United Nations.

From New York Times • Feb. 24, 2022

The comments prompted alarm among U.S. officials who feared he was once again formulating a casus belli ahead of possible new military action against Ukraine.

From Washington Post • Feb. 3, 2022

In such a febrile atmosphere, the risk of a misunderstanding or unplanned escalation is greater, and Russia could use such an incident as a casus belli.

From Reuters • Jan. 14, 2022

He used the emotional force of the occasion, channeled through his rhetoric, to quietly shift the political ground and redefine the casus belli in a way that suited him.

From "Words Like Loaded Pistols" by Sam Leith