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 /

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.

Origin of casus belli

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