| Acronym | Definition |
|---|
| SU | Shut Up |
| SU | SketchUp (Google application) |
| SU | Stumble Upon (website) |
| SU | Straight Up |
| Su | Sunnuntai (Finnish: Sunday) |
| SU | Statens Uddannelsesstøtte (state education grant and loan scheme in Denmark) |
| SU | Siehe Unten (German: see below) |
| SU | Sonic Underground (TV show) |
| SU | Special Unitary (mathematics; group theory) |
| SU | Service Uniform (US Navy) |
| SU | Sihala Urumaya (political party, Sri Lanka) |
| SU | Supply-Use (tables) |
| SU | Stabsunteroffizier |
| SU | Svar Udbedes (Danish: Reply Requested, on invitations) |
| SU | Siegburg/Rhein-Sieg-Kreis (German license plate) |
| SU | Stat Unit |
| SU | Sukhoi, Pavel Osipovich (aircraft designer) |
| SU | Safe, Undetected Failure |
| SU | Sindh University Jamshoro (Pakistan) |
| SU | Sulphonyl Urea (herbicide) |
| SU | Spitali Ushtarak (Albanian: Military Hospital) |
| SU | Society of the Sisters of St. Ursula (religious order) |
| SU | Submarine Unqualified |
| SU | Surd'Universo ( Portugal) |
| SU | Sources and Uses |
| SU | Silpakorn University (Bangkok, Thailand) |
| SU | Shenandoah University (Winchester, VA, USA) |
| SU | Seattle University |
| SU | Screw You |
| SU | search unit (US DoD) |
| SU | Soviet Union |
| SU | Shareholders United (campaigning to keep Manchester United independent) |
| SU | Subscriber Unit |
| SU | Switch User (Linux) |
| SU | Strayer University |
| SU | Shepherd University (Shepherdstown, WV) |
| SU | Siliman University (Philippines) |
| SU | Sofia University (Sofia, Bulgaria) |
| SU | Aeroflot (airline code) |
| SU | Single User |
| SU | Sullivan University (Lexington, Kentucky) |
| SU | Start Up (various organizations) |
| SU | Sudbury (Ontario city) |
| SU | South Underground |
| SU | Southwestern University (Georgetown, Texas) |
| SU | Sydney University (Sydney, Australia) |
| SU | Standard Unit |
| SU | Samakhodnaya Ustanovka (Soviet self-propelled gun) |
| SU | Sims Unleashed (game) |
| SU | Signal Unit (CCS #7 ITU-T) |
| SU | Shiraz University |
| SU | Sahlgrenska Universitetssjukhuset (Gothenburg, Sweden hospital) |
| SU | Situational Understanding (US Army) |
| SU | Stetson University |
| SU | Student Union |
| SU | Sonic Unleashed (video game) |
| SU | Skinners Union |
| SU | Springfield University (The Simpsons) |
| SU | Sabanci University (Istanbul, Turkey) |
| SU | Schreiner University (Kerrville, Texas) |
| SU | Surface Unit |
| SU | Sub Urban Area (terrain type) |
| SU | Salisbury University |
| SU | Scoville Unit (heat level of chili peppers) |
| SU | Supervisory (duties) |
| SU | Stroke Unit (medicine) |
| SU | Service Unit |
| SU | Susquehanna University (Selinsgrove, PA) |
| SU | Spousal Unit |
| SU | Scripture Union |
| SU | Stockholm University (Sweden) |
| SU | Superb Used (philately) |
| SU | Canceled-To-Order (special philatelic cancel; hobby usage) |
| SU | Superuser |
| SU | Belarus (ISO Country Identifier) |
| SU | Samford University (Birmingham, AL, USA) |
| SU | Selectable Unit (IBM) |
| SU | Sensor Unit |
| SU | Signaling Unit |
| SU | Software Update |
| SU | Southern University |
| SU | Stanford University (Stanford, CA) |
| SU | Storage Unit |
| SU | Students' Union |
| SU | Sub Unit (USMC) |
| SU | Sudan |
| SU | Sukhoi |
| SU | Syracuse University (Syracuse, NY) |
| SU | Shippensburg University |
| SU | Switching Unit |