| Abbreviation | Definition |
|---|---|
| OS | Original Solution |
| Os | Osmium |
| OSAC | Outer Space Acid Cat |
| OSBP | Ohio State Biochemistry Program |
| OSI | Orchestra Of Strategic Influence |
| OSI | Ordinary Stuffed Isotopes |
| OSNA | One Step Nucleic acid |
| OSSCAR | Organic Sulfur Sequential Chemical Analysis Robot |
| OTA | Ortho-Tolidine-Arsenite |
| OTC | Open Tubular Column |
| OTDF | Overall Temperature Distribution Factor |
| OV | Organic Vapor |
| OVA | Organic Vapor Analyzer |
| OVA | Ovalbumin |
| OVC | Outer Vacuum Container |
| OVI | Organic Volatile Impurities |
| OVM | Organic Vapor Monitor |
| OWP | On Weight Of Polypropylene |
| OXA | OXanilic Acid |
| OXD | OXadiazole Derivative |