conceived or appearing as if conceived by an unrestrained imagination; odd and remarkable; bizarre; grotesque: fantastic rock formations; fantastic designs.
fanciful or capricious, as persons or their ideas or actions: We never know what that fantastic creature will say next.
imaginary or groundless in not being based on reality; foolish or irrational: fantastic fears.
extravagantly fanciful; marvelous.
incredibly great or extreme; exorbitant: to spend fantastic sums of money.
highly unrealistic or impractical; outlandish: a fantastic scheme to make a million dollars betting on horse races.