Source : WordNet®

house of cards
     n 1: 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" [syn: {bubble}]
     2: an unstable construction with playing cards; "he built three
        levels of his cardcastle before it collapsed" [syn: {cardhouse},
         {card-house}, {cardcastle}]