casus belli

1. 1.

   an event used to justify starting a war

   Broaderbeginning

Questions about casus belli

What does casus belli mean?

casus belli means "an event used to justify starting a war".

Is casus belli a common word?

casus belli is banded "Rare" — specialist or archaic — most readers will not have met it. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.