| Abbreviation | Definition |
|---|---|
| UC | Unacceptable Content |
| UCA | Unauthorized Computer Access |
| UCAR | User Control Access Right |
| UCE | Unsolicited Commercial E-mail |
| UCF | Unregistration ConFirmation |
| UCK | Universal Correlation Key |
| UCU | Universal Control Unit |
| UDACT | Universal Digital Alarm Communicator Transmitter |
| UDID | Unique Device IDentifier |
| UDID | Universal Design IDentity |
| UE | Unlikely Event |
| UES | User Electronic Signature |
| UFO | Un-Filtered Offering |
| UG | Up Gateway |
| UGO | User, Group, and Other |
| UI | Unauthorized Information |
| UIC | User Identification Code |
| UID | Unique IDentifier |
| UIM | User Identity Module |
| UIN | User Identification Number |