Definition of casus belli in English:

casus belli

Line breaks: casus belli
Pronunciation: /ˌkeɪsəs ˈbɛlʌɪ
, ˌkɑːsʊs ˈbɛli

noun (plural same)

An act or situation that provokes or justifies a war.
More example sentences
  • As the Romans liked a casus belli to justify their aggressive activities, it is not always possible to be certain about the real circumstances behind their intervention.
  • France countered by getting Russia to propose a general congress, intended to isolate Austria and provoke a casus belli.
  • The failure to disarm is probably a casus belli.


Latin, from casus (see case1) and belli, genitive of bellum 'war'.

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