A speculative scheme that depends on unstable factors that the planner cannot control:
— His proposal was nothing but a house of cards.

synonym: bubble.

Roget 328: brittleness etc. adj.; fragility, friability, frangibility, fissibility^†; house of cards, house of glass.   

Roget 160: weakness etc. adj.; debility, atony^†, relaxation, languor, enervation; impotence etc. 158; infirmity; effeminacy, feminality^†; fragility, flaccidity; inactivity etc. 683.    anaemia, bloodlessness, deficiency of blood, poverty of blood.    declension of strength, loss of strength, failure of strength; delicacy, invalidation, decrepitude, asthenia^†, adynamy^†, cachexy^†, cachexia [Med.], sprain, strain.    reed, thread, rope of sand, house of cards.    softling^†, weakling; infant etc. 129; youth etc. 127.    ... show more

An unstable construction with playing cards.

synonyms: card-house, cardcastle, cardhouse.

Dutch: kaartenhuis
Polish: domek z kart