a cataclysm resulting from a destructive sea wave caused by an earthquake or volcanic eruption; "a colossal tsunami destroyed the Minoan civilization in minutes"
an obvious change of public opinion or political sentiment that occurs without leadership or overt expression; "there was a ground swell of antiwar sentiment"
an unstable construction with playing cards; "he built three levels of his cardcastle before it collapsed"
a speculative scheme that depends on unstable factors that the planner cannot control; "his proposal was nothing but a house of cards"; "a real estate bubble"