Art, generally pictorial rather than sculptural, that depicts the unreal in a realistic manner. Works of 'fantastic art' may use Biblical, allegorical, or symbolic subject matter as departure points. The term is used to describe the work of artists from many periods and countries, but, most often, products of art tradition in Europe and the post-Columbian Americas. The term is not used for works from Medieval Europe, nor Oceanic or Asiatic cultures before the 20th century. While works from these latter cultures may exhibit depictions of the monstrous, mythological, or the unseen world, they lack the elements of eccentricity and willfull grotesquery that are hallmarks of the 'fantastic.'

Source: Art & Architecture Thesaurus

http://vocab.getty.edu/page/aat/300056485