(n.) One given to daydreams.

Don Quixote Quixote Walter Mitty absence of mind absentmindedness absorption abstractedness abstraction bemusement brown study castle-building daydream daydreaming depth of thought dream dreamer dreamer of dreams dreaming engrossment enthusiast escapist fantasy fantasying fit of abstraction idealist lotus-eater mooning moonraking muse musefulness musing muted ecstasy pipe dream pipe-dreaming preoccupation prophet reverie rhapsodist romancer romantic romanticist seer stargazing study trance utopian utopianist utopianizer visionary wishful thinker woolgathering