casus belli

[ key-suhs bel-ahy, bel-ee; Latin kah-soos bel-lee ]

noun

, plural ca·sus bel·li [key, -s, uh, s , bel, -ahy, bel, -ee, kah, -soos , bel, -lee].

1. an event or political occurrence that brings about a declaration of war.

casus belli

/ ˈkɑːsʊs ˈbɛliː /

noun

1. an event or act used to justify a war
2. the immediate cause of a quarrel

Word History and Origins

Origin of casus belli¹

1840–50; < New Latin: literally, occurrence of war

Word History and Origins

Origin of casus belli¹

literally: occasion of war

Example Sentences

Only in the past several months has “religious freedom” gained momentum as a casus belli, appearing in Ukrainian and U.S. religious media and now embraced by evangelical Republicans.

From Salon

"We will not respond by talking about 'casus belli' or not, we will respond with concrete actions," he said.

From Reuters

Having lied to her own constituents, fanning their fears of a rigged election, she then claimed their suspicions as a casus belli.

From New York Times

Critical voices challenging Putin’s casus belli and highlighting Russia’s isolation, the atrocities committed daily by Russian troops and the disastrous costs of the conflict for Russia have been all but silenced.

From Washington Post

Holocaust Memorial Museum has dismissed Russia’s use of “genocide” as a casus belli as “groundless and egregious.”

From Washington Post

Related Words

• affront
• harassment
• indignity
• insult