| Acronym | Definition |
|---|
| TOS | Teacher Over Shoulder (chat) |
| TOS | Terms Of Service |
| TOS | Temporarily Out of Stock |
| TOS | The Original Series (Star Trek) |
| TOS | The Other Side |
| TOS | Type Of Service |
| TOS | Tales of Symphonia (video game) |
| TOS | The Operating System |
| TOS | The Opposite Sex |
| TOS | Thoracic Outlet Syndrome |
| TOS | Town of Salem (gaming) |
| TOS | Tales of Suspense (comic) |
| TOS | Toshiba Corporation (stock symbol; Japan) |
| TOS | Talend Open Studio (software) |
| TOS | Terminal Operating System |
| TOS | The Obesity Society (est. 1982; Silver Spring, MD) |
| TOS | The Old Schoolhouse (magazine) |
| TOS | Terminate on Sight (G-Unit album) |
| TOS | Temple of Set |
| TOS | Temporarily Out of Service |
| TOS | The Objective Standard |
| TOS | Tennessee Ornithological Society (est. 1915) |
| TOS | Top of the Stack |
| TOS | Tape Operating System |
| TOS | the Other Service |
| TOS | Tape on Substrate |
| TOS | Testing Operation System |
| TOS | Technical and Office Systems |
| TOS | Temporary Out of Service |
| TOS | Taligent Object Services |
| TOS | the Other Spammers |
| TOS | Top of Stack |
| TOS | Tiny Operating System |
| TOS | Transactions on Storage |
| TOS | The Oceanography Society |
| TOS | Technical Operations Specialist (various companies) |
| TOS | Trial of Scar (obstetrics) |
| TOS | Terminate on Site |
| TOS | Tactical Operations System |
| TOS | Theosophical Order of Service (est. 1908) |
| TOS | Tactical Operations Support (US TSWG) |
| TOS | Terminal Operation System |
| TOS | Time of Sale |
| TOS | Title of Show (musical) |
| TOS | Task Order Solicitation (engineering; Los Angeles, CA) |
| TOS | Treatment Outcome Score (healthcare) |
| TOS | Tramiel Operating System (Atari ST/TT operating system) |
| TOS | Time On Station |
| TOS | Trusted Operating System |
| TOS | Transfer Orbit Stage |
| TOS | Technician on Site |
| TOS | Tape Operating System (IBM) |
| TOS | The Organic Standard (journal) |
| TOS | Tip of the Spear |
| TOS | Techniques, Ouvriers et de Service (French: Technical and Service Workers) |
| TOS | Top of Steel |
| TOS | Taken on Strength |
| TOS | Traffic Operations System |
| TOS | Top Of Slab (concrete) |
| TOS | Transfer of Sovereignty (Baghdad, Iraq) |
| TOS | Trucial Oman Scouts (Unite Arab Emirates) |
| TOS | Time on Stream |
| TOS | Tender of Service |
| TOS | Tromso, Norway - Tromso/Langes (Airport Code) |
| TOS | Total Outstanding Shares (Canada) |
| TOS | Type Of Shipment |
| TOS | Tennessee Orthopaedic Society |
| TOS | Taux d'Onde Stationnaire (French: Standing Wave Ratio) |
| TOS | Time Of Search |
| TOS | Training Objective Statement |
| TOS | Tunnels et Ouvrages Souterrains (French: Tunnels and Underground Structures; journal) |
| TOS | Tactical Operations Squadron (USAF) |
| TOS | Tactical Oceanographic Summary |
| TOS | Teller Operations Specialist (banks) |
| TOS | Terminal Oriented System |
| TOS | Turbine Overspeed (aero engines) |
| TOS | Tone Operated Squelch (two-way radio) |
| TOS | Tactical Operator Station |
| TOS | Terminal Oriented Software |
| TOS | Testing Operations System |
| TOS | Top of Shelf |
| TOS | Track on Search |
| TOS | Transition Operational State |
| TOS | Transparent Optical Switch |
| TOS | Transmission Optimization System |
| TOS | TIROS (Television Infrared Observation Satellite) Operational Satellite (US NOAA) |
| TOS | Take-Off-Structure (electric substation structure) |