| Acronym | Definition |
|---|
| OPT | Options (File Name Extension) |
| OPT | Optional Practical Training |
| OPT | Optional |
| OPT | Office of Pupil Transportation (New York, NY) |
| OPT | Optical |
| OPT | Optimization |
| OPT | Optimized Production Technology |
| OPT | Optimum |
| OPT | Ocean Power Technologies (UK & USA) |
| OPT | Occupied Palestinian Territory |
| OPT | Outpatient Physical Therapy |
| OPT | Overprint (philately) |
| OPT | Output Transformer (electronics) |
| OPT | Office des Postes et Télécommunications |
| OPT | Outreach Project Tool (groupware software) |
| OPT | Other People's Time |
| OPT | Open Protocol Technology |
| OPT | Office de Promotion du Tourisme Wallonie-Bruxelles (Sint-Gillis, Belgium) |
| OPT | Outdoor Payment Terminal |
| OPT | Ounces Per Tonne (mining) |
| OPT | Orthopantomogram |
| OPT | Operational Planning Team |
| OPT | Open Plug-In Technology |
| OPT | Ocean Pout (FAO species name code ) |
| OPT | Options Pricing Theory (finance) |
| OPT | Oxford Placement Test (language proficiency) |
| OPT | Optional Modification |
| OPT | Office des Postes et Télécommunications de Nouvelle-Calédonie (Office of Mail and Telecommunications, New Caledonia) |
| OPT | Office of Telecommunications Policy |
| OPT | Offshore Pipeline Technology |
| OPT | Operations Planning Team |
| OPT | Overlegorgaan Post En Telecommunicatie (Dutch Consultative Committee Post and Telecommunication of the Ministry of V&W) |
| OPT | Onboard Performance Tool (Boeing) |
| OPT | Organization of Parents and Teachers |
| OPT | Oil Pressure Transmitter |
| OPT | Optoelectronic Physics and Technology (IEEE conference) |
| OPT | Operations Planning Tool |
| OPT | Organic Power Technologies Ltd (Victoria, BC, Canada) |
| OPT | Oil Penetration Test |
| OPT | Organizational Planning Technique |
| OPT | Open-Shell Perturbation Theory |
| OPT | Onstreet Parking & Trees |
| OPT | Officer Physical Training |
| OPT | Options Power Trader (newsletter) |
| OPT | Orthopedic Physical Therapy (various locations) |
| OPT | Oceanside Photo and Telescope (Oceanside, CA) |