OTS
- Air Force Officer Training School
- Anacortes Airport
- Georg Ots
- Izh (river)
- MS Georg Ots
- Ocean Therapy Solutions
- Octadecyltrichlorosilane
- Off-the-shelf (disambiguation)
- Office for Transportation Security
- Office of Tax Simplification
- Office of Technical Service
- Office of Thrift Supervision
- Office of Transport Security
- Officers Training School, Bahtoo
- Officers' Training School RAAF
- Ohr Torah Stone
- OpenTimestamps
- Operator Training Simulator
- Opportunity to see
- Orbital Test Satellite
- Orchestra at Temple Square
- Order of the Solar Temple
- Organization for Tropical Studies
- Organization of Turkic States
- Orthodox Theological Seminary, Kottayam
- Over-the-shoulder shot