| Abbreviation | Definition |
|---|---|
| OXL | L-4-Oxalysine |
| OXM | OXamic Acid, C2 H4 N1 O2 |
| OXS | 2-OXalosuccinic Acid, C6 H6 O7 |
| OXT | Oxytocin |
| OXY | Oxygen |
| OYCE | Outstanding Young Chemical Engineer |
| OYCE | Outstanding Young Chemical Engineers |
| OZG | OZone Generator |
| OZM | OZone Machine |
| OZR | OZone bottle Rinser |
| OZT | OZone Tester |
| OZW | Ozonized Water |
| P | Particle |
| P | Phosphorus |
| P | Plus |
| P | Pressure |
| P | Proton |
| P/A | Presence/Absence |
| P2O | Plastic to Oil |
| PA | Phosphatidic Acid |