English abbreviations from orta to osa
- ORTA (Office of Research and Technology Applications)
- ORTF (Office de Radiodiffusion Television Francaise)
- ORTSU (Organized Reserve Training Service Training Unit)
- ORU (Oruro Airport)
- ORV (Robert (Bob) Curtis Memorial Airport (FAA: D76))
- ORW (Olentangy River Wetland Research Park)
- ORX (Operational Receiver)
- ORY (Orly International Airport)
- OS (Operating System)
- O.S. (Left eye)
- OS/2 (Operating System/2)
- OS/360 (IBM 360 operating system (1960s))
- OS&D (Over, Short & Damage (Report))
- OS/OD (Overall size/overall diameter)
- OS2 (Operating System/2)
- OSA (Overseas Contingency Operation Support Assignments)
- O.S.A. (Ordo [Eremitarum] Sancti Augustini (Augustinians))
