vis ma·jor 
(v
ĭs m
āj
ər)
n. pl. vi·res ma·jo·res (v
ī′r
ēz m
ə-jôr
ēz, -j
ŏr
-)
Law An overwhelming, unanticipated, and unpreventable event, usually caused by a natural force, the occurrence of which may exempt a party from performing the obligations of a contract. Also called force majeure.
[Latin vīs māior : vīs, force + māior, greater.]