catastrophe, disaster -- (a state of extreme (usually irremediable) ruin and misfortune; "lack of funds has resulted in a catastrophe for our school system"; "his policies were a disaster")
calamity, catastrophe, disaster, tragedy, cataclysm -- (an event resulting in great loss and misfortune; "the whole city was affected by the irremediable calamity"; "the earthquake was a disaster")
disaster -- (an act that has disastrous consequences)