The computer was defective is the sentence that shows a correct use of a Thesaurus.
Something that is defective has a fault in it and does not work correctly so that it could be used as a synonym of BROKEN.
The thesaurus is a reference work containing lists words grouped together according to similarity of meaning (containing synonyms and sometimes antonyms), in contrast to a dictionary, which provides definitions for words, and generally lists them in alphabetical order. The main purpose of this type of book is to "find the word, or words, by which [an] idea may be most fitly and aptly expressed."
