Webster's Revised Unabridged Dictionary · 1913

Casus

Casus , noun

[Latin]

An event; an occurrence; an occasion; a combination of circumstances; a case; an act of God. See the Note under Accident.
Collocations (3)
Casus belli , an event or combination of events which is a cause war, or may be alleged as a justification of war.
Casus fortuitus , an accident against which due prudence could not have provided. See Act of God, under Act.
Casus omissus , a case not provided for by the statute.