casus belli

[ key-suhs bel-ahy, bel-ee; Latin kah-soos bel-lee ]
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noun,plural ca·sus bel·li [key-suhs bel-ahy, bel-ee; Latin kah-soos bel-lee]. /ˈkeɪ səs ˈbɛl aɪ, ˈbɛl i; Latin ˈkɑ sus ˈbɛl li/.
  1. an event or political occurrence that brings about a declaration of war.

Origin of casus belli

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

Words Nearby casus belli Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use casus belli in a sentence

British Dictionary definitions for casus belli

casus belli

/ Latin (ˈkɑːsʊs ˈbɛliː) /

nounplural casus belli (ˈkɑːsʊs ˈbɛliː)
  1. an event or act used to justify a war

  2. the immediate cause of a quarrel

Origin of 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