| Abbreviation | Definition |
|---|---|
| TST | Transitional Stored Ticket |
| TSZ | Temporary Security Zone |
| TTH | Tiger Tree Hashing |
| TVA | Time Variance Authority |
| TVC | Trivial Vernam Cipher |
| TVD | Total Virus Defence |
| TW | Tequila Worm |
| TWS | TrustWorthy Software |
| TYM | Taking Your Machine |
| U | Unlocked |
| U | Userid |
| UA | Unlimited Access |
| UAC | Unified Administration Center |
| UAC | User Account Control |
| UACT | User Account Control Team |
| UAF | User Authorization File |
| UAR | User Access Rights |
| UAS | User Accounts Security |
| UBAC | User Based Access Control |
| UBD | Uber0n Back Door |