world-building

Noun

worldbuilding (uncountable)

1. The conception and description of a fictional world, often as the setting of a work of fiction, particularly in speculative fiction.
   • The purpose of worldbuilding isn't just to do a cool exercise, but to give a sense of place — and all of your thought experiments absolutely have to result in something vivid and alive.2013 February 8, Charlie Jane Anders, “7 Deadly Sins of Worldbuilding”, in io9, archived from the original on 25 Nov 2016
2. (obsolete) Scientific research into the creation of the Earth and its geological features.
3. (obsolete) The world of imagination of novelists, poets, etc.