fantascience

Blend of fantastic +‎ science or fantasy +‎ science.

fantascience (uncountable)

1. (now rare) A genre of fiction which combines scientific and fantastic elements.
   • 1989, Harlan Ellison, Harlan Ellison's Watching, Los Angeles, C.A.: Underwood–Miller, →ISBN, page 78:

     Silent Running is a myth anchored in materialism and realism, despite its fantascience trappings.

• Jesse Sheidlower, editor (2001–2025), “fantascience, n.”, in Historical Dictionary of Science Fiction.