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 the Doctor's universe. (TV: Doomsday)
History
In the 20th century, 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 [+]Loading...["Falls the Shadow (novel)"])
In March 2005, he Ninth Doctor told Jenn if she tried to skip her ICT A-Level the whole world would be doomed. (PROSE: Have You Seen This Man? [+]Loading...["Have You Seen This Man? (short story)"])
The new webmaster of Who is Doctor Who? after Clive's death noticed that coverage of the Dummy Massacre was disappearing from World Media by 2 April 2005. He also sought to prove the truth about the Doctor to the world. (PROSE: The Doctor Was Involved in the Dummy Massacre [+]Loading...["The Doctor Was Involved in the Dummy Massacre (short story)"])
After the defeat of the Slitheen family on 7 March 2006, Mickey Smith (TV: World War Three [+]Loading...["World War Three (TV story)"]) wrote on his website the morning after about how he was watching the world forget the events that unfolded in the past couple of days. He also mentioned how the Ninth Doctor saved the world. (PROSE: Hoax This! [+]Loading...["Hoax This! (short story)"])
By 2007, one of David R's interests was "revealing the truth about [what is] really happening in the world". (PROSE: Who Am I? [+]Loading...["Who Am I? (feature)"])
In the 26th century, Eric Klieg wanted to use Cyber-Technology to become "master of the world." (TV: The Tomb of the Cybermen [+]Loading...["The Tomb of the Cybermen (TV story)"])