It means she used a lot of big words. Most of them are not used in the proper context, so many people think she used words like "angry", looked them up in a thesaurus, and changed it to "chagrin". Chagrin =/= angry.
Stephenie Meyer essentially raped a thesaurus when writing the Twilight 'saga'. To avoid any further attacks or permanent damage to the mental health of thesauruses everywhere, each must now carry a standard issue rape kit. Get a free kit for you thesaurus by calling 62442 today, but hurry, stocks are going fast. Smeyer is EVERYWHERE!