From Longman Dictionary of Contemporary EnglishMicrosoftMi‧cro‧soft /ˈmaɪkrəʊˌsɒft $ -ˌsɔːft/ trademark a US company which is one of the world's largest and most important producers of computer software. It is known especially for its Windows operating system, which is used on most personal computers, for Microsoft Word, a popular word-processing program, and for Internet Explorer, a popular program for searching the Internet. The company was started by Bill Gates.