fantastic [fanˈtʰas.tɪk(ʰ)]adjective 5noun 1forms 3 adjective5 •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. •extremely good"I had a simply fantastic vacation, and I can't wait to tell you all about it!" •Not believable; implausible; seemingly only possible in fantasy. •(no longer used) Given to fanciful ideas, impulsive; irrational.She was a frightened fool, and she was fantastic, and I suppose that, at that time, she really cared for that imbecile. — 1915 •(no longer used) Resembling fantasies in irregularity, caprice, or eccentricity; irregular; grotesque.There at the foot of yonder nodding beech, / That wreathes its old fantastic roots so high. — 1750 noun1 •(no longer used) A fanciful or whimsical person. formsfantastics · more fantastic · most fantastic