n. An extremely small, lightweight computer that has many of the functions and features of a full-size personal computer.
At a computer trade show in Germany, South Korea's Samsung Electronics Co., Taiwan's Asustek Computer Inc. and China's second-largest PC-maker, Founder Group, said they will each sell PCs based on a design that Microsoft code-named Origami. The companies are formally calling the products Ultra-Mobile Personal Computers, or UMPCs.

The devices run Microsoft's Windows XP operating system and feature additional Microsoft software that lets users control the PC with the touch of a finger. The Origami devices, which are expected to be about 2 pounds and come with a screen that measures 7 inches diagonally, are a smaller follow-on to tablet PCs, which are pen-input devices about the size of standard notebook PCs.
—Robert A. Guth & Don Clark, “Microsoft Plans Hand-Held PC,” The Wall Street Journal, March 10, 2006
Movielink, a broadband video-on-demand (VOD) download service, announced that it has teamed with Microsoft to offer premium Hollywood content to the Ultra-Mobile PC (UMPC) devices announced by Microsoft.

Through the arrangement, Movielink will be the premier brand and provider of video content for the UMPC Program Launcher, enabling users the ability to download Movielink content directly to their UMPC device.
—“Movielink Teams with Microsoft to Offer Hollywood Content to Ultra-Mobile PC Devices,” Wireless News, March 10, 2006
2005 (earliest)
As an alternative for those who love to roam with multi-function gadgets, Intel Corp, the giant chip manufacturer, has plans to introduce what it calls the Ultra Mobile PC (UMPC) next year.
—“Ultra-Mobile PC: More powerful than the average digital assistant,” The Nation, November 12, 2005