monopoly A market in which one business is overwhelmingly dominant; also, the dominant business itself. One of four basic competitive market structures. Related Related Articles: Glossary: copyrightGlossary: patentHow the Best and Worst Airlines Are DifferentHow a Contest Can Encourage IngenuityHow Tiger Woods Helped Nike Sell Golf Balls Ann Mills Share This Previous ArticleM1 Next Articleopen market operations December 17, 2020