U
UA - Unmanned Aircraft (An aircraft which is intended to operate with no pilot on board.)
UAC - User Agent Client (Application that creates a request for initiating a communication session within the Session Initiation Protocol (SIP), a signaling protocol used in Voice over Internet Protocol (VoIP), communication sessions.)
UAS - unmanned aircraft systems (An aircraft and its associated elements which are operated with no pilot on board.)
UAS - User Agent Server (A server for a Session Initiation Protocol (SIP), a signaling protocol used in Voice over Internet Protocol (VoIP) communication sessions, which is responsible for handling all routing and signaling involved in VoIP calls.)
UAT - user acceptance testing (Software application testing, used during development, done by the end-user team responsible for testing the software against specific scenarios or business cases, such as customer look-up or account history look-up.)
UAV - Unmanned Aerial Vehicle (An aircraft capable of flying without a pilot, normally under constant control by a ground operator.)
UBR - unspecified bit rate (A connectionless communications channel, (meaning the sender does not worry about establishing or maintaining a connection - establishing the connection is the responsibility of another protocol), that does not promise a specific data throughput rate. UBR relates to Quality of Service (QoS) capability, in a situation where customers cannot, and do not need to, control their traffic rate.)
UC - Unified Communications (Term for real-time applications which use Session Initiation Protocol (SIP), a signaling protocol used in VoIP communication sessions to set up and break down the sessions, such as video conferencing, multimedia, instant messaging, and online gaming.)
UDDI - Universal Description, Discovery and Integration (A service-oriented architecture (SOA) service, which is an XML-based web-based registry listing of available services offered by a business, which will also provide consumers a mechanism for looking up and contacting the business.)
UDI - unique device identifier (In the medical field, an identification device capable of identifying individual medical devices, similar to the network interface card (NIC) address identifying individual chips burned into microchip circuit boards during manufacture.)
UDP - User Datagram Protocol (A connectionless Transmission Control Protocol (TCP) used to carry messages (referred to as "datagrams" in UDP), without establishing or maintaining contact with the destination computer.)
UID - user identifier (Name for a user/account identifier in the UNIX and Linux operating systems.)
UII - unique investment identifier (Term used by federal agencies to identify investments in IT systems or hardware. (Replaced the Unique Project Identifier (UPI) term.))
UL - Underwriters Laboratory
UML - Unified Modeling Language (A method used in system project analysis which graphically illustrates use cases or scenarios with stick-figures in a walk-through of a system, showing each step a user might take when using a system.)
UPI - unique project identifier (Former term used in federal systems for identifyng investment assets for tracking for capital planning and investment control. UPI was replaced by the term unique investment identifier (UII).)
UPS - uninterruptible power supply (A backup power supply with battery packs intended to supply temporary power to a computer unit during power outages.)
UPT - unsophisticated persistent threat (A type of threat that does not require advanced technical skills, although available advanced technology may increase the threat capability, combined with the intent to focus efforts on a specific target over a long period of time.)
URG - Urgent
URL - uniform resource locator (The method or means of locating and connecting to a website, which involves a 2-part address: 1) the address "www.mywebaddress.com" known as a Fully Qualified Domain Name (FQDN) and 2) the method of accessing the address (which specific protocol to use), such as through Hypertext Transfer Protocol (http) - "http://www,mywebaddress.com" )
USB - universal serial bus (An external peripheral bus standard designed to bring plug and play (PnP) capability for attaching peripherals externally to a PC. USB was initially developed by Intel engineers in the early 1990s, then transferred to a group forum of computer and software companies. A bus is a collection of parallel electrical wires used for transferring data, first appearing in 1964 in a computer built by Digital Equipment Corporation (DEC), intended to reduce or avoid the special cooling requirements of existing mainframe computers, as well as to allow for sharing by all devices in the computer.)
US-CERT - United States Computer Emergency Readiness Team (Agency within the federal government which collects and analyzes data on threats to U.S. information systems and provides information and warnings about malware, cyber attacks, and threats.)
USCYBERCOM - United States Cyber Command (U.S. unified military command, established in May 2010, to deal with cyberspace issues - intended to coordinate intelligence gathering, planning, and operations focused on cyber security and cyber warfare activities between and on behalf of the various branches of the U.S. military.)
USGCB - United States Government Configuration Baseline (Guidelines for federal agencies for secure configurations of operating systems, Web browsers, and other computer workstation features.)
UT - unsophisticated threats (Threats posed by individuals or organizations with little experience, understanding, or expertise, who have access to advanced tools, which can be used to carry out high-level attacks.)
UTM - unified threat management (The concept of implementing multipurpose security devices that perform a wide variety of functions, including firewall, proxy, virtual private network (VPN), and data loss prevention functions.)
UUID - universal unique identifier (Function within a Distributed Computing Environment (DCE) used to uniquely identify users, resources, and components.)
UUV - Unmanned Underwater Vehicle (A remotely operated vehicle used for underwater operations.)