| UAC | User Account Control | - | Human Genome |
| UART | Universal Asynchronous Receiver/Transmitter | - | Human Genome |
| UCITA | Uniform Computer Information Transaction Act | - | Human Genome |
| UDDI | Universal Description, Discovery And Integration | - | Human Genome |
| UDP | UDP - User Datagram Protocol | - | Human Genome |
| UIN | Universal Internet Number | - | Human Genome |
| ULSI | Ultra Large Scale Integration | - | Human Genome |
| ULTRAATA | Ultra AT Attachment | - | Human Genome |
| ULTRADMA | Ultra Direct Memory Access | - | Human Genome |
| UMB | Upper Memory Block | - | Human Genome |
| UML | Unified Modeling Language | - | Human Genome |
| UNC | Universal Naming Convention | - | Human Genome |
| UNIX | Universal Interactive Executive / Uniplexed Information And Computing System | - | Human Genome |
| UPS | Uninterruptible Power Supply | - | Human Genome |
| URI | Uniform Resource Indicator | - | Human Genome |
| URL | Uniform Resource Locator | - | Human Genome |
| USB | Universal Serial Bus | - | Human Genome |
| USENET | User Network | - | Human Genome |
| USR | US Robotics | - | Human Genome |
| UTP | Unshielded Twisted Pair | - | Human Genome |
| UUCP | UNIX-to-UNIX Copy | - | Human Genome |
| UUENCODE | UNIX-to-UNIX Encode | - | Human Genome |
| UBI | unique billing identifier
| - | Human Genome |
| UBR | unspecified bit rate
| - | Human Genome |
| UBS | unclassified but sensitive
| - | Human Genome |
| UFR | unspecified frame relay
| - | Human Genome |
| UI | user interface
| - | Human Genome |
| UIFN | Universal International Free Phone Number
| - | Human Genome |
| UITN | Universal International Toll-Free Number
| - | Human Genome |
| ULH | ultra longhaul
| - | Human Genome |
| UM | unified messaging
| - | Human Genome |
| UMS | Unified Messaging Services
| - | Human Genome |
| UMTS | Universal Mobile Telecommunications System
| - | Human Genome |
| UN | United Nations
| - | Human Genome |
| UNI | user-to-network interface
| - | Human Genome |
| UPSR | unidirectional path switch ring
| - | Human Genome |
| US-CERT | United States-Computer Emergency Readiness Team
| - | Human Genome |
| USC | United States Code
| - | Human Genome |
| USF | Universal Service Fund
| - | Human Genome |
| USNO | United States Naval Observatory
| - | Human Genome |
| USG | United States Government
| - | Human Genome |
| UTC | universal time code
| - | Human Genome |
