Castle in the air

/ˈkɑːs(ə)l ɪn ðiː ˈɛə/ noun

noun ·Rare ·Advanced level

Definitions

Noun
  1. 1
    A desire, idea, or plan that is unlikely to ever be realized; a visionary project or scheme; a daydream, an idle fancy, a near impossibility. idiomatic

    "Many times ſuch men when they come to themſelves, tell ſtrange things of Heauen and Hell, what viſions they haue ſeene; […] The like effects almost are to bee ſeene in ſuch as are awake: How many Chimæras, Anticks, golden mountaines, and Caſtles in the Aire doe they build vnto themſelves?"

  2. 2
    absentminded dreaming while awake wordnet

Example

More examples

"Many times ſuch men when they come to themſelves, tell ſtrange things of Heauen and Hell, what viſions they haue ſeene; […] The like effects almost are to bee ſeene in ſuch as are awake: How many Chimæras, Anticks, golden mountaines, and Caſtles in the Aire doe they build vnto themſelves?"