cloud-built

cloud-built (comparative more cloud-built, superlative most cloud-built)

1. unsubstantial or imaginary.
   • 1761, Hew Dalrymple, Woodstock. An Elegy:

     on the summit of a cloud-built height

   • 1799, Analytical Review:

     both of them so flimsy and cloud-built, that they are unable to withstand even the soft impressions of their adverse debility.

   • 1908, Richard Watson Gilder, Vanishing City:

     Of love undying and of endless praise
     ⁠For beauty only—chief of all thy kind;
     Immortal, even because of thy brief days;
     ⁠Thou cloud-built, fairy city of the mind!

• castle in the air

• “cloud-built”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.