fantastic

Etymology

Borrowed from Middle French fantastique, borrowed from Late Latin phantasticus, borrowed from Ancient Greek φᾰντᾰστῐκός (phantastikós, “imaginary, fantastic; fictional”), ultimately from Proto-Indo-European *bʰeh₂- (“to shine”). Equivalent to fantasy + -tic. Doublet of fantastique.

adj

1. 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.
   At the base of the whole process by which divinities and demons were created, and rites for their propitiation and placation established, lay Fear - fear stimulating the imagination to fantastic activity. 1920, Edward Carpenter, Pagan and Christian Creeds, New York: Harcourt, Brace and Co., published 1921, page 13
2. 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.
   And indeed, when in the writings of Paracelſus I meet with ſuch Phantaſtick and Un-intelligible Diſcourſes as that Writer often puzzels and tyres his Reader with, father'd upon ſuch excellent Experiments, as though he ſeldom clearly teaches, I often find he knew ; me thinks the Chymiſts, in their ſearches after truth, are not unlike the Navigators of Solomons Tarſhiſh Fleet, who brought home from their long and tedious Voyages, not only Gold, and Silver, and Ivory, but Apes and Peacocks too ; For ſo the Writings of ſeveral (for I ſay not, all) of your Hermetick Philoſophers preſent us, together with divers Subſtantial and noble Experiments, Theories, which either like Peacocks feathers make a great ſhew, but are neither ſolid nor uſeful ; or elſe like Apes, if they have ſome appearance of being rational, are blemiſh'd with ſome abſurdity or other, that when they are Attentively conſider'd, makes them appear Ridiculous. 1661, Robert Boyle, “THE CONCLUSION”, in The Sceptical Chymist: or Chymico-Physical Doubts & Paradoxes, Touching the Spagyrist's Principles Commonly call'd Hypostatical, As they are wont to be Propos'd and Defended by the Generality of Alchymists. Whereunto is præmis'd Part of another Diſcourſe relating to the ſame Subject, London: J. Caldwell, pages 429–430
   Since 1 part in 100,000 would imply that one could put a Shuttle up each day for 300 years expecting to lose only one, we could properly ask "What is the cause of management's fantastic faith in the machinery?" June 6, 1986, Richard Feynman, “Personal observations on the reliability of the Shuttle”, in Presidential Commission on the Space Shuttle Challenger Accident, Report to the President
3. Resembling fantasies in irregularity, caprice, or eccentricity; irregular; grotesque.
4. 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!"

noun

1. (archaic) A fanciful or whimsical person.