The third Boolean operator, NOT, eliminates a specific search term or group of search terms. For instance, in a search for literature related to the search for a missile defense system during the Reagan presidency, we may retrieve unwanted articles pertaining to the movie Star Wars. Using the search strategy "star wars NOT cinema " essentially means that all documents that contain the phrase "cinema" will be removed from your search for Star Wars.

The NOT operator is used very infrequently and should only be used when you are confident you will not eliminate articles or other information that could be useful.

Many databases guide you by including these Boolean operators in their search interface.