| Abbreviation | Definition |
|---|---|
| OIS | Operational Intercommunication System |
| OIS | Optical Image Stabilizer |
| OIS | Orbiter Insertion Stage |
| OIS | Orbiter Instrumentation System |
| OISR | Open Item Status Report |
| OISSP | Office of Interim Space Station Program |
| OIT | Orbiter Integrated Test |
| OIV | Oxidizer Isolation Valve |
| OIVS | Orbiter Interface Verification Set |
| OJT | On-the-Job Training |
| OL | Open Loop |
| OL | Operational Left |
| OL | OverLay |
| OL | OverLoad |
| OLBIN | Optical Long Baseline Interferometry News (NASA forum) |
| OLDB | On-Line Data Bank |
| OLE | Orbital Life Extension |
| OLEM | Orbital Life Extension Maneuver |
| OLER | Orbital Life Extension Rocket |
| OLEV | Orbital Life Extension Vehicle |