It is useful because it prevents you from having to use the same word over and over and adds variety to your work.
(That being said, you shouldn't just go through and replace words in your writing with big, "impressive" words as people will see through that and your writing will not be as fluid.)
Roget's Thesaurus Roget's Thesaurus
Thesaurus
Meanings of words are found in the dictionary.
A thesaurus is a helpful reference source to find an antonym for "clever." Some antonyms for clever include obtuse, simple, or unintelligent.
Wiki Answers, a dictionary, or a thesaurus. (thess OH russ)
Probably a thesaurus, but a dictionary may be some help!
A dictionary or thesaurus
A thesaurus would be the best reference source to find several synonyms for the word "sauntered." Thesauruses provide lists of synonyms and related words that can be used as alternatives in writing to avoid repetition.
thesaurus
You could research "walk" in a thesaurus and then use past tense to create synonyms for "walked." You may actually find "walked" in a thesaurus.
thesaurus is the answer!
A thesaurus or a dictionary