The Collaborative International Dictionary of English v.0.48:

Laputan \La*pu"tan\, a.
   Of or pertaining to Laputa, an imaginary flying island
   described in Gulliver's Travels as the home of chimerical
   philosophers. Hence, fanciful; preposterous; absurd in
   science or philosophy. "Laputan ideas." --G. Eliot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Laputan
    adj 1: relating to or characteristic of the imaginary country of
           Laputa or its people
    2: not practical or realizable; speculative; "airy theories
       about socioeconomic improvement"; "visionary schemes for
       getting rich" [syn: airy, impractical, visionary,
       Laputan, windy]