Writers of fantasy are not assumed to be sticklers for language. After all, they revel in the invented and magical. But when describing things that do not exist, choosing the right word is key.
When C.S. Lewis responded to a letter from a young American fan in 1956—not long before the publication of his final Narnia volume, The Last Battle—he first told her that there is no uniform “Good English.” Language is never a fixed thing. One has to tailor prose for time and place.
Lewis then gives her a few rules for the road:
1. Always try to use the language so as to make quite clear what you mean and make sure your sentence couldn’t mean anything else.
2. Always prefer the plain direct word to the long, vague one. Don’t implement promises, but keep them.
3. Never use abstract nouns when concrete ones will do. If you mean “More people died” don’t say “Mortality rose.”
4. In writing. Don’t use adjectives which merely tell us how you want us to feel about the thing you are describing. I mean, instead of telling us a thing was “terrible,” describe it so that we’ll be terrified. Don’t say it was “delightful”; make us say “delightful” when we’ve read the description. You see, all those words (horrifying, wonderful, hideous, exquisite) are only like saying to your readers, “Please will you do my job for me.”
5. Don’t use words too big for the subject. Don’t say “infinitely” when you mean “very”; otherwise you’ll have no word left when you want to talk about something really infinite.
Clarity is paramount, in writing as in life.