1. mischance, misfortune, misadventure, mishap, accident, blow, reverse, adversity, affliction. Disaster, calamity, catastrophe, cataclysm refer to adverse happenings often occurring suddenly and unexpectedly. A disaster may be caused by carelessness, negligence, bad judgment, or the like, or by natural forces, as a hurricane or flood: a railroad disaster. Calamity suggests great affliction, either personal or general; the emphasis is on the grief or sorrow caused: the calamity of losing a child. Catastrophe refers especially to the tragic outcome of a personal or public situation; the emphasis is on the destruction or irreplaceable loss: the catastrophe of a defeat in battle. Cataclysm, physically an earth-shaking change, refers to a personal or public upheaval of unparalleled violence: a cataclysm that turned his life in a new direction.