WordNet (r) 3.0 (2006):

force majeure
    n 1: a natural and unavoidable catastrophe that interrupts the
         expected course of events; "he discovered that his house
         was not insured against acts of God" [syn: act of God,
         force majeure, vis major, inevitable accident,
         unavoidable casualty]

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "force majeure":
   act of God, amperage, armipotence, authority, beef, black power,
   brute force, certainty, charge, charisma, clout, cogence, cogency,
   compulsion, dint, drive, duress, effect, effectiveness,
   effectuality, energy, fate, fatefulness, flower power, force,
   forcefulness, full blast, full force, indefeasibility,
   ineluctability, inescapableness, inevasibleness, inevitability,
   inevitable accident, inevitableness, inexorability, inflexibility,
   influence, irrevocability, main force, main strength, mana, might,
   might and main, mightiness, moxie, muscle power, necessity,
   pizzazz, poop, potence, potency, potentiality, power, power pack,
   power structure, power struggle, powerfulness, predetermination,
   prepotency, productiveness, productivity, puissance, pull, punch,
   push, relentlessness, sinew, steam, strength, strong arm,
   superiority, superpower, sureness, unavoidable casualty,
   unavoidableness, uncontrollability, undeflectability,
   unpreventability, unyieldingness, validity, vehemence, vigor, vim,
   virility, virtue, virulence, vis major, vitality, wattage,
   weight