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X1(1) A cable TV entertainment operating system from Comcast. Introduced in 2012, the Xfinity X1 platform lets people use tablets and smartphones as an auxiliary interface.
(2) A desktop search program for Windows from X1 Technologies, Inc., Pasadena, CA (www.x1.com) that includes a file viewer for more than 225 formats. Introduced in 2004, X1 provides search capabilities for Office documents, various e-mail messages, as well as PDF and ZIP files. See desktop search.