ORS
- Collision/reaction cell
- ISO/IEC JTC 1/SC 6
- List of legal abbreviations
- Michigan Office of Retirement Services
- ORS-1
- ORS-5
- Oculo-respiratory syndrome
- Old Red Sandstone
- Olfactory reference syndrome
- Operational Research
- Operational Research Society
- Operationally Responsive Space Office
- Oral rehydration solution
- Orcas Island Airport
- Oregon Revised Statutes
- Orlando Riva Sound
- Ors
- Orthopaedic Research Society
- Otorhinolaryngological Research Society
- Oulx
- Ovarian remnant syndrome
- Overseas Research Scholarship
- Oxygen reduction system
- Paquita Ors
- SPARK (rocket)
- Shoot 'em up