My thoughts (in case anyone cares) on whether or not the author should avoid words the viewpoint character wouldn't use. Whether or not the narrative should use words that the character would not, is an aspect of point of view, and depends on the distance that you want to achieve between the narration and the protagonist. In a first person narrative you should always only use worlds the protagonist knows and would use, obviously, but in third person you have a wide range of stylistic choices. Using language the same way the viewpoint character would is a good way to establish character, and to achieve a close connection between the reader and that character, but sometimes there are reasons not to do so. Here are some examples of times when I, personally might avoid using a characters' voice (I'm sure there are more): The protagonist's voice may not suit the tone you want to achieve. The protagonist's vocabulary may be too limited, making narrative written in that way too clunky to be read. The story requires some distance either in emotion or time from the protagonist -- like when the narrator is the protagonist grown up, or when the protagonist will die during the story. I feel the story is appropriate to an "omniscient" narrative voice. Perhaps I want the freedom to follow several characters around, but the consistancy of a single voice, for example. Hope someone finds this musing useful/informative. :)