- UAV
- UK
- Ultrasound
- Underdeveloped Countries
- Underground
- Underground Storage Tanks
- Underwater Diving
- Unemployment
- Uniforms
- United Airlines Flight 93
- United Kingdom
- Universities
- Unix
- Unmanned Aerial Vehicle
- Upholstery
- Upper Extremities
- Uranium
- Urban Areas
- Urban Fire Protection
- Urban Fires
- Urban Legends
- Urban Planning
- Urban Renewal
- Urban Search Rescue
- Urban Wildland Interface
- USAR
- User Fees
- USSR
- Utilities