Fantastic

From Middle French fantastique

Full definition of fantastic

Existing in or constructed from fantasy; of or relating to fantasy; fanciful.He told fantastic stories of dragons and goblins.His fantastic post-college plans had all collapsed within a year of graduation.She had a fantastic view of her own importance that none of her colleagues shared.
Not believable; implausible; seemingly only possible in fantasy.The events were so fantastic that only the tabloids were willing to print them.She entered the lab and stood gaping for a good ten minutes at the fantastic machinery at work all around her.
Resembling fantasies in irregularity, caprice, or eccentricity; irregular; grotesque.

T. GrayThere at the foot of yonder nodding beech,
That wreathes its old fantastic roots so high.

Wonderful; marvelous; excellent; extraordinarily good or great (used especially as an intensifier)."I had a simply fantastic vacation, and I can't wait to tell you all about it!"

(based in fantasy rather than reality) fabulous, fantastical
(extravagantly fanciful and unrealistic) foolish, hare-brained, unrealistic, wild
(incredibly wonderful) brilliant, fabulous, splendid, super, wonderful