| Acronym | Definition |
|---|
| UI | User Interface |
| UI | Unemployment Insurance |
| UI | Useful Information |
| UI | University of Illinois |
| UI | Universitas Indonesia (University of Indonesia) |
| UI | University of Iowa |
| UI | Ultra Instinct (manga) |
| UI | Unique Identifier |
| UI | University of Idaho |
| UI | Urinary Incontinence |
| UI | Urban Industrial (target for air strike) |
| UI | Under the Influence |
| UI | Under Instruction |
| UI | Urban Institute (Washington, DC, USA) |
| UI | University of Isfahan (Iran) |
| UI | University of Ibadan (Nigeria) |
| UI | United Illuminating Company |
| UI | Unix International |
| UI | Unnumbered Information |
| UI | User Interface Machine |
| UI | Unidad Internacional (Spanish: International Unit; measurement) |
| UI | User Integration |
| UI | Universal Interface (NEC) |
| UI | Unit Interval |
| UI | University of Incheon (South Korea) |
| UI | Unit of Issue |
| UI | Unit Interface |
| UI | University of Indianapolis |
| UI | Unit Injector |
| UI | Undergraduate Instructor (education) |
| UI | Unemployment Initial (DOL) |
| UI | Uranium Institute (London, UK) |
| UI | Unit Inventory |
| UI | Upgrade Insurance |
| UI | Utility Infielder |
| UI | Unalaska Island (Alaska) |
| UI | Unidentified Individual (courts) |
| UI | Union Interparlementaire |
| UI | Unión Interparlamentaria (Spanish) |
| UI | Fatty Acid Unsaturation Index |