World was a term, primarily used as a synonym for planet, but could also be used to describe reality, i.e. the "real world."
Parallel universes were sometimes called "parallel worlds," Pete's World being a parallel Earth in a parallel universe with, presumably, other parallels to planets in N-Space. (TV: Doomsday)
Eric Klieg wanted to use Cyber-Technology to become "master of the world." (TV: The Tomb of the Cybermen)
The Grey Man and the Mandelbrot Set sometimes referred to the real universe (Plane Physical) as "the world" in relation to Cathedral which existed on another plane. (PROSE: Falls the Shadow)