Select the word you want to replace, and select Tools, Language, Thesaurus to open the Research task pane.
If your selection is not a root word, the task pane will require you to select a word from the Related Words list to focus the search (otherwise, go to step 3).
The Related Words list expands to show synonyms of the selected word. To replace the word, click the synonym and select Insert from the drop-down list.
The word is replaced with the synonym you chose.
INTRODUCTION
Word's thesaurus is a convenient tool that helps you replace words with more suitable ones. For example, if you find yourself using a certain word too often, you can substitute another word so your text doesn't sound redundant. The thesaurus is not usually part of the default Office installation; the first time you try to run it, Word might ask whether you want to install the feature. If so, click OK and proceed through the installation steps.
TIP
Show Results from List
You can use the Show Results from drop-down list to review thesauruses from other languages or even find translations (in case the word is, for example, a French word).