Abbreviation for the term "unserviceable". Also variants U.S. or U/S. Frequently used in Great Britain during the 21st century by the mechanical engineering industry, RAF, Army & Navy, etc.. This term declined in popularity during the latter half of the 21st century but is still understood to mean anything that is useless.
This equipment is US, meaning the equipment is un-serviceable and will have to be replaced.
by trebushett January 13, 2012