search engine

noun

1. a computer program that searches documents, especially on the World Wide Web, for a specified word or words and provides a list of documents in which they are found.

noun

1. computing a service provided on the internet enabling users to search for items of interest

Web sites or software that search the Internet for documents that contain a key word, phrase, or subject that is specified by the user to the search engine. Each engine has its own method of searching for information.