What is the meaning of fantastic?

adjective

• Ludicrously odd.
  • usage: "Hamlet's assumed antic disposition"; "fantastic Halloween costumes"; "a grotesque reflection in the mirror"
  • synonyms: antic, fantastical, grotesque
• Extraordinarily good or great; used especially as intensifiers.
  • usage: "a fantastic trip to the Orient"; "the film was fantastic"; "a howling success"; "a marvelous collection of rare books"; "had a rattling conversation about politics"; "a tremendous achievement"
  • synonyms: grand, howling, marvelous, marvellous, rattling, terrific, tremendous, wonderful, wondrous
• Fanciful and unrealistic; foolish.
  • usage: "a fantastic idea of his own importance"
  • synonyms: wild
• Existing in fancy only."fantastic figures with bulbous heads the circumference of a bushel- Nathaniel Hawthorne
  • synonyms: fantastical
• Extravagantly fanciful in design, construction, appearance.
  • usage: "Gaudi's fantastic architecture"