| Abbreviation | Definition |
|---|---|
| OBS | Operational Biomed Sensors |
| OBS | Operational Biomedical Sensor |
| OBS | Operational Biomedical System |
| OBSS | Orbiter Boom Sensor System |
| OBT | On-Board Time |
| OBU | On Board Unit |
| OBV | Oxidizer Bleed Valve |
| OC | On Center |
| OC | On-Condition |
| OC | Open Circuit |
| OC | Operations Controller |
| OC | Operations Coordinator |
| OC | Orbital Check |
| OC | Overcurrent |
| OCALC | Oklahoma City Air Logistics Center |
| OCC | Office of Contract Compliance |
| OCD | Operational Capability Development |
| OCDR | Orbiter Critical Design Review |
| OCDU | Optics Coupling Data Unit (G&N) |
| OCE | Ocean Color Experiment |