U
- unserviceable
- unsigned integer
- unsolicited behavior
- unsolvable problem
- unstructured data
- unsupervised learning
- untrusted process
- up-down counter
- up-front planning
- update
- upgrade
- uplink
- upload
- upload speed
- upper bound
- upper case
- upper memory
- UPS
- upside-down mouse
- upsizing
- UPSR
- uptime
- upward compatibility
- URI
- URL
- URL parameter
- URN
