| Acronym | Definition |
|---|
| OST | Original Sound Track |
| OST | Official Soundtrack |
| OST | Out of School Time (after-school care programs) |
| OST | Office of Science and Technology |
| OST | On Second Thought |
| OST | Office of the Secretary of Transportation |
| OST | Old Spanish Trail |
| OST | Office of the Special Trustee for American Indians |
| OST | Organisation Scientifique du Travail (French: Scientific Labor Organization) |
| OST | Offline Store |
| OST | Oblate School of Theology |
| OST | Open Storage (software) |
| OST | Outer Space Treaty |
| OST | On-Screen Takeoff (construction planning) |
| OST | Office of Secure Transportation (US Department of Energy) |
| OST | Observatoire des Sciences et Techniques (French: science and technology observatory) |
| OST | Optimal Solutions and Technologies (Washington, DC) |
| OST | Online Service Provider |
| OST | Operations Support Team |
| OST | Order Ship Time |
| OST | Operational Sea Training |
| OST | Open Skies Treaty |
| OST | Oxford Superconducting Technology (New Jersey) |
| OST | Office of Security Transition |
| OST | Originating Station Treatment |
| OST | Open Source Teaching |
| OST | Orthogonal Space-Time (coding scheme) |
| OST | Optical Standards Tester (Carcadiant Systems) |
| OST | Operational Suitability Test |
| OST | Oral Specimen Test |
| OST | Order & Shipping Time |
| OST | Objective, Strategy, Tactics (business/marketing) |
| OST | Odonata Survey of Texas |
| OST | Operational Requirements Document Support Team |
| OST | Observational Sequence Table |
| OST | OPTEC System Team |
| OST | Over-Stress Test |
| OST | Optical Switch Technology |
| OST | Ormat Solar Turbine |
| OST | Off-Station Trainer (US Air Force) |
| OST | Oscillating Sand Abrasion Test |
| OST | Original Star Trek (TV series) |
| OST | Open Source Technologies (various locations) |
| OST | Out-Service Training (various locations) |
| OST | Opioid Substitution Therapy (drug dependency) |
| OST | Out of State Transfer (various applications) |