| Abbreviation | Definition |
|---|---|
| OBX | Outer Banks |
| OC | Orange Coast |
| OCR | Over Consolidation Ratio |
| OCSG | Outer Continental Shelf (Gulf of Mexico) |
| OCTG | Oil Country Tubular Goods |
| OGS | Oklahoma Geological Survey |
| OH8 | Olduvai Hominid |
| OIB | Ocean Island Basalt |
| OK | Old Keokuk |
| OMC | Old Mine Cut |
| OMC | On-line Map Creation |
| OPUS | Online Positioning User Service |
| OVSP | Offset-source Vertical Seismic Profile |
| OXN | Oxnard aquifer |
| P | Peninsula |
| PA | Position Approximate |
| PACS | Physics and Astronomy Classification Scheme |
| PALE | Paleoclimate of Arctic Lakes and Estuaries |
| PB | Primary Basin |
| PB | Prosodic Boundary |