| Acronym | Definition |
|---|
| OT | Off Topic (newsgroups, message boards, etc.) |
| OT | Old Testament |
| OT | Occupational Therapy |
| OT | Overtime |
| OT | Other |
| OT | On Topic |
| OT | Over the Top |
| OT | Offensive Tackle (football) |
| OT | Occupational Therapist |
| OT | On Tour |
| OT | On Target |
| OT | Outlined (graphic design) |
| OT | One Time (action code) |
| OT | Operación Triunfo |
| OT | Out of Town |
| OT | Open Top (holster) |
| OT | Open Top |
| OT | Old-Timer |
| OT | Ordinary Time (Catholicism) |
| OT | Open Type (font format) |
| OT | Ortsteil (German: Locality) |
| OT | Original Trilogy (Star Wars) |
| OT | Oxytocin |
| OT | Oregon Trail |
| OT | Oil Tank |
| OT | Overtone |
| OT | Operating Thetan (Scientology) |
| OT | Output Transformer (electronics) |
| OT | Other Transactions |
| OT | Oliver Twist |
| OT | Order Type (mathematics) |
| OT | Old Tappan (New Jersey) |
| OT | Optimality Theory (linguistics) |
| OT | Oral Testimony |
| OT | Open Transport (networking) |
| OT | Operating Time |
| OT | Over Travel |
| OT | Object Technology |
| OT | Operation Theater |
| OT | Organizational Training (Process Area; Capability Maturity Model Integration) |
| OT | Off Treatment (cancer) |
| OT | Overseas Territory |
| OT | Osmium Tetroxide |
| OT | Order Taker |
| OT | Omni-Tek (Anarchy Online gaming faction) |
| OT | Optical Telescope |
| oT | Ohne Text (German: No Text content) |
| OT | Overtemperature |
| OT | Original Trainer (Pokemon) |
| OT | Office of Telecommunications |
| OT | Onegai Teacher (anime) |
| OT | Orientation Tour |
| OT | Off-Tank (gaming) |
| OT | Optical Transceiver |
| OT | Obstructing Traffic (traffic law) |
| OT | Oberer Totpunkt (German: Top Dead Center) |
| OT | Ouachita Trail |
| OT | Observing Tool |
| OT | Orquesta Típica (Spanish: Typical Orchestra) |
| OT | Office Terminal (GTE) |
| OT | Ownership Transition |
| OT | Opportunity Taken |
| OT | Observer Trainer (military exercises) |
| OT | Observer-Target |
| OT | Okinawa-Te (martial art style) |
| OT | Optical Tracker |
| OT | Orascom Telecom Holding SAE (stock symbol) |
| OT | The Overthere (Everquest) |
| OT | Oregon Trunk Railway |
| OT | Orchestra Toronto (Canada) |
| OT | Organisasi Terlarang (Indonesian: prohibited organization) |
| OT | Operational Threshold |
| OT | Original Tracing |
| OT | Optical Transponder |
| OT | Orbital Telescope |
| OT | Operational Test/ing |
| OT | Ortho Technician |
| OT | Optical Translator |
| OT | Optical Terminator (O/E Land, Inc) |
| OT | Otelco Telecommunications LLC |
| OT | Officer Trainee/Training |
| OT | (USN Rating) Ocean Systems Technician |
| OT | Osservatorio Astronomico de Torino (Italian) |
| OT | Operation Team (various organizations) |