In the ribbon of a Word file (2007 Edition), which starts from “Home” and ends with “View,” the last but one is “Review.” Click that, and you will see “Thesaurus” in the middle of the 2nd column. Use it often, NOT to search for a fancy word, but a more scientific word when you need to write: “We got the data from …”
Type in "thesaurus" (or "get") in a Word file, and highlight it before clicking "Thesaurus" in the ribbon, you will see to the right of your Word file: