Dictionary.com
definitions

casus belli

[ key-suh s bel-ahy, bel-ee; Latin kah-soo s bel-lee ]
/ ˈkeɪ səs ˈbɛl aɪ, ˈbɛl i; Latin ˈkɑ sʊs ˈbɛl li /
SEE MORE SYNONYMS FOR casus belli ON THESAURUS.COM

noun, plural ca·sus bel·li [key-suh s bel-ahy, bel-ee; Latin kah-soos bel-lee] /ˈkeɪ səs ˈbɛl aɪ, ˈbɛl i; Latin ˈkɑ sus ˈbɛl li/.

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

RELATED WORDS

harassment, indignity, affront, insult, grievance, motivation, justification, annoyance, taunt, challenge, incentive, instigation, reason, dare, offense, injury, cause, vexation, inducement, grounds

Nearby words

casualwear, casuarina, casuist, casuistic, casuistry, casus belli, cat, cat and mouse, cat brier, cat burglar, cat cafe

Origin of casus belli

1840–50; < New Latin: literally, occurrence of war
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for casus belli

casus belli

/ Latin (ˈkɑːsʊs ˈbɛliː) /

noun plural casus belli (ˈkɑːsʊs ˈbɛliː)

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

Word Origin for casus belli

literally: occasion of war
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for casus belli

casus belli

n.

1849, from Latin casus "case" (see case (n.1)) + belli, genitive of bellum "war" (see bellicose). An act justifying war.

Online Etymology Dictionary, © 2010 Douglas Harper