Facepalm Factor: a highly subjective factor in world building that happens when elements of the world are so strange, so out of the ordinary, or even so silly, that readers lose suspension of disbelief in such a way that they facepalm. Examples of the Facepalm Factor might include rainbow farting unicorns and sparkly vampires. A more extreme form of the Facepalm Factor is the Headdesk Factor.
Mythopoeia: “Myth making” A term created by J.R.R. Tolkien for his poem of the same name. The poem describes the wonder of myth creation in favor of cold rationalism. It’s what we do when we create a world that’s real and alive, no matter how imaginary it may be.
Random Apostrophe Syndrome: the tendency for fantasy and science fiction writers to try to make words sound more exotic by adding apostrophes that add nothing to the pronunciation of the word, and that do not indicate contractions. R.A.S. is subjective, as some are not bothered by it, although it does tend to alienate readers who know about the proper use of apostrophes, as it shows that the world builder did not bother to put in the extra effort to make the language authentic.
Trope: a concept or motif that appears in various media enough to be a part of a cultural consciousness. Character archetypes, such as Hero, Villain, and Sidekick are a kind of trope, as are different aspects of fantasy or science fiction, such as Our Vampires Are Different, the Evil Empire, and Crystal Dragon Jesus. (The wiki TV Tropes is a wonderful place to find these, but be warned; entering this site can end up turning into a rabbit hole of hours of wasted time finding more tropes than you ever imagined.)