vismajor

vis ma·jor (vĭs māʹjər) n. Law pl. vi·res ma·jo·res (vī'rēz mə-jôrʹēz, -jŏrʹ-)

An overwhelming force of nature having unavoidable consequences that under certain circumstances can exempt one from the obligations of a contract.

  [Latin vīs māior: vīs, force + māior, greater.]

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