The always-delightful Max Gladstone discusses the good and bad of repetition in fiction.
We notice repetition as a negative. But some words do not just repeat as tics, or not merely as tics. What is a book, but a constellation of words? Each time a word is used, it accumulates new meaning from its context, and lends the meanings it has accumulated—in your particular text, and in others—to the sentence. In this way languages can be ennobled or (for a time, at least) poisoned—if you’re an American, do you feel the same way about the word ‘great’ that you did six years ago? If you’re a particular kind of nerd, when I began that sentence just now with ‘What is a book,” did you hear it followed by “a miserable little pile of secrets”?
Within a text, repeated words draw connections. What sorts of things in this book are ghosts? Is this car a ghost? This memory? Is the white of her hat a ghostlike white? “The ghost of a smile?” Fantasy and science fiction prose worldbuilding sings—or, to be honest, works at all—by loading vocabulary in this way: ’uplift’ in Brin, ‘Guardian’ in Jemisin (or the beautiful side-loading of ‘suss’ into the invented sensory verb ‘sess’), iris in Heinlein’s off-referenced ‘the door irised open.’ McKillip’s ‘riddles’ and ‘beasts’ are quite particular sorts of riddles and beasts, as are Jordan’s ‘channeling,’ and Tolkien’s ‘ring.’