A nondiversified investment that is closely correlated with a single industry or line of business.
A company whose business is restricted to one activity or sector. In contrast, a conglomerate is a business that has many different types of business activities.
Dealing with a specific category of product rather than a mix of products. It is generally used in marketing to indicate that a company is specializing in one area. For example, "xyz is betting on a pure play in desktop PCs" means that xyz sells nothing but desktop PCs.