| Abbreviation | Definition |
|---|---|
| ODCB | Ortho Di Chloro Benzene |
| ODCB | orthodichlorobenzene |
| OER | Oxygen Evolution Reaction |
| OF | Oxygen Free |
| OFHC | Oxygen Free High Conductivity |
| OFT | Overall Flow Time |
| OH | Hydroxide |
| OH | Hyroxide ion |
| OH | Oxygen And Hydrogen |
| OH2 | Water |
| OIHA | Ortho Iodo Hippuric Acid |
| OILRIG | Oxidation Is Losing, Reduction Is Gaining |
| OILRIG | Oxidization Is Losing, Reduction Is Gaining |
| OILS | Open Integrated Learning System |
| OLA | Oil Low Acid |
| OLCC | On Line Chemistry Course |
| OLCC | On Line Chemistry Courses |
| OLF | Oubain-Like Immunoreactive Factor |
| OM | Organic Matter |
| OM | Orientational Melting |