Fantastic a. : Existing only in imagination; fanciful; imaginary; not real; chimerical.

Fantastic a. : Having the nature of a phantom; unreal.

Fantastic a. : Indulging the vagaries of imagination; whimsical; full of absurd fancies; capricious; as, fantastic minds; a fantastic mistress.

Fantastic a. : Resembling fantasies in irregularity, caprice, or eccentricity; irregular; oddly shaped; grotesque.

Fantastic n. : A person given to fantastic dress, manners, etc.; an eccentric person; a fop.

Example:
Steps to Fantastic sex from start to finish?

Taxonomy
character, phenomenon, free encyclopedia, supernatural explanation, the Grotesque, hesitation, original meaning, Witty Characters, literary genres, Tzvetan Todorov, supernatural elements, search, literary term that describes, conflated, structuralist theory, critic, liminal, leaves.

Defination from the web:
Fantastic is a literary term that describes a quality of other literary genres, and in some cases is used as a genre in and of itself, although ... The term was originated in the structuralist theory of critic Tzvetan Todorov in his work The Fantastic. ...