What is "ultrabook"

n. (context computing English) a very lightweight and thin portable computer the areal size of a notebook computer or subnotebook, modeled after the archetypal http://en.wikipedia.org/wiki/Macbook%20Air

Ultrabook was created as a specification and trademarked brand by Intel for a class of high-end subnotebooks designed to feature reduced bulk without compromising battery life. They used low-power Intel Core processors, solid-state drives, and unibody chassis to help meet these criteria. Due to their limited size, Ultrabooks typically omitted common laptop features such as optical disc drives and Ethernet ports. Ultrabook is a portmanteau of words ultraportable and notebook.