unreal or imaginary
so extreme as to challenge belief; incredible
exceedingly large or great
marked by extravagant fantasy or eccentricity; unrealistic
informal wonderful; eccentric
He looked fantastic in his velvet jacket
fantastical adj
fantasticality /-ʹkaliti/ noun
fantastically adv
fantasticalness noun
Middle English fantastic, fantastical via French and late Latin from Greek phantastikos producing mental images, from phantazein to present to the mind and phantazesthai to imagine, both from phantos visible. In the 16th–19th cent. the spellings phantastic, and phantasy fantasy1, were also used