fantast

noun

definition: one given to fanciful, impractical dreams; visionary.

Quotation:

“To come down to earth” is, in ordinary speech, to get to reality, to face the facts, and to be practical. On the other hand, “to have your head in the clouds” is to be a dreamer and a fantast, though oddly and curiously, the Christian notion of heaven, the abode of God and therefore the seat of ultimate reality, is traditionally symbolized as a situation where everyone floats in the sky. (Alan Watts, Cloudhidden, Whereabouts Unknown: A Mountain Journal)