If you're ever trying to describe what it is you do, and people just look at you funny when you say "I'm a world builder" - say "I do mythopoeia" and watch their face...just watch.
The founding father of fantasy, Mr. J.R.R. Tolkien, revived this word in the 1930s. Mythopoeia means - a narrative genre in modern literature and film where a fictional mythology is created by the writer of prose or other fiction. The idea is actually from the Hellenic Greeks in the fashion of the Homeric epic the Illiad and the Odyssey.
There are many examples of this now, but Tolkien was among the pioneers in modern times.
One last bit of trivia: Tolkien was never knighted. Queen Elizabeth did award him with the Order of the British Empire (one level below knighthood) in early 1973. He passed away September 2, 1973. It is thought that perhaps if he'd lived longer to see the Silmarillion get published in 1977, he may have died Sir J.R.R. Tolkien.
I like to think that even if he were knighted it would mostly be an honorary title that didn't change his hobbit-like outlook - much like Merry and Pippin being conferred with the titles of Rohan and Gondor.