USIM Application Toolkit, a standard which enables the USIM to initiate actions which can be used for various value-added services delivered to 3G mobile devices (USAT is the equivalent of STK for 3G cellular networks)
United States Army Transport, a designation given to United States Army troop transports; the abbreviation is placed before the name of the ship
USA Triathlon, the national governing body for the multi-sport disciplines of triathlon, duathlon, aquathlon and winter triathlon in the United States
UNIQUE-SAT, a special case of the Boolean Satisfiability problem (Computer Science)