Meaning of house of cards

house' of cards'

Pronunciation: [key]
  1. a structure or plan that is insubstantial and subject to imminent collapse, as a structure made by balancing playing cards against each other: The scheme is so overly complicated that it's likely to prove to be just another house of cards.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.