Source : Webster's Revised Unabridged Dictionary (1913)

Visionary \Vi"sion*a*ry\, a. [Cf. F. visionnaire.]
   1. Of or pertaining to a visions or visions; characterized
      by, appropriate to, or favorable for, visions.

Visionary \Vi"sion*a*ry\, n.; pl. {Visionaries}.
   1. One whose imagination is disturbed; one who sees visions
      or phantoms.

   2. One whose imagination overpowers his reason and controls
      his judgment; an unpractical schemer; one who builds
      castles in the air; a daydreamer.

Source : WordNet®

visionary
     adj : not practical or realizable; speculative; "airy theories
           about socioeconomic improvement"; "visionary schemes
           for getting rich" [syn: {airy}, {impractical}, {Laputan}]
     n 1: a person given to fanciful speculations and enthusiasms with
          little regard for what is actually possible
     2: a person with unusual powers of foresight [syn: {illusionist},
         {seer}]

Source : Free On-Line Dictionary of Computing

visionary
     
        1. One who hacks vision, in the sense of an Artificial
        Intelligence researcher working on the problem of getting
        computers to "see" things using TV cameras.  (There isn't any
        problem in sending information from a TV camera to a computer.
        The problem is, how can the computer be programmed to make use
        of the camera information?  See {SMOP}, {AI-complete}.)
     
        2. [IBM] One who reads the outside literature.  At IBM,
        apparently, such a penchant is viewed with awe and wonder.
     
        [{Jargon File}]