| Acronym | Definition |
|---|
| OTP | One Time Password |
| OTP | Office of the Prosecutor (International Criminal Court; Netherlands) |
| OTP | One Time Programmable (electronics) |
| OTP | One Time Pad |
| OTP | One Time Payment (customer service) |
| OTP | On the Phone (chat) |
| OTP | Obligatorisk Tjenestepensjon (Norwegian: Mandatory Occupational Pension) |
| OTP | Office of the Premier (various locations) |
| OTP | On-Time Performance |
| OTP | Over Temperature Protection |
| OTP | One Touch Phone (smartphone) |
| OTP | Order Transaction Processing |
| OTP | One Time Payment |
| OTP | Open Trading Protocol |
| OTP | One Time Programmable |
| OTP | on the Phone |
| OTP | Opposite Track Path |
| OTP | On Track Plant (rail vehicle; UK) |
| OTP | Over the Phone |
| OTP | Operator Training Program (various organizations) |
| OTP | Open Telecom Platform |
| OTP | Opposite Track Path (DVD mastering system) |
| OTP | Online Team Play (gaming) |
| OTP | Outside the Perimeter (people living outside the I-285 perimeter of Atlanta, GA) |
| OTP | Open Trading Protocol (for purchasing) |
| OTP | Off the Page |
| OTP | Opioid Treatment Program |
| OTP | One Term President |
| OTP | One-Trick Pony (Paul Simon song/album) |
| OTP | Open Training Platform (various organizations) |
| OTP | Offender Treatment Program (various locations) |
| OTP | Offer to Purchase |
| OTP | Order to Pay |
| OTP | One True Pairing |
| OTP | Optical Transport Platform (various companies) |
| OTP | Orientation Training Program (various organizations) |
| OTP | Officers Training Program (various locations) |
| OTP | Office of Telecommunications Policy |
| OTP | Oregon Transportation Plan |
| OTP | Occupational Training Program (various organizations) |
| OTP | Oil Treatment Plant |
| OTP | Other Tobacco Product (taxation designation) |
| OTP | Bucharest, Romania - Otopeni (Airport Code) |
| OTP | Operations Test Plan (US NASA) |
| OTP | Owner's Title Policy (real estate) |
| OTP | Orlando Theatre Project (Orlando, FL) |
| OTP | Outpatient Treatment Program |
| OTP | Outdoor Therapeutic Program |
| OTP | Odznaka Turystyki Pieszej (Polish PTTK badge) |
| OTP | Olympic Transport Plan (UK) |
| OTP | Ore Transport Permit (Department of Environment and Natural Resources; Philippines) |
| OTP | Operational Test Piece |
| OTP | Outline Test Plan |
| OTP | On the Piss |
| OTP | Other Transfer Payment (various organizations) |
| OTP | Operational Test Plan |
| OTP | On the Pause |
| OTP | Operational Test Procedure |
| OTP | Országos Takarék Pénztár (Hungarian: General Saving Bank) |
| OTP | One True Pair/Pairing (fan fiction, erotica) |
| OTP | Overtime Personnel |
| OTP | Openland Tree-Planting |
| OTP | One Team Partner |
| OTP | Orbital Time Processor |
| OTP | Other Theater Project (Cleveland, Ohio) |
| OTP | Other Trustworthy Person (PEZ collectors) |
| OTP | Operating & Transition Plan |
| OTP | Optional Time Period |
| OTP | Optical Technology Project |
| OTP | Operational Trial Period |
| OTP | Oh, the Profanity! (blog) |
| OTP | Operations Training Package |
| OTP | Off the Pigs (band) |