| Abbreviation | Definition |
|---|---|
| OPP | Order Pizza for Programmer |
| OR | Logical OR |
| ORB | Object Request Broker |
| ORCA | Oxygen Regulator Console Assembly |
| OSAM | Orbit Servicing Assembly and Manufacturing |
| OSAT | Outsourced Semiconductor Assembly and Test |
| OSAT | Outsourced Semiconductor Assembly and Testing |
| OSAT | Outsourced Semiconductor Assembly Test |
| OSL | Optimization Subroutine Library |
| OSN | Operand Segment Number |
| OT | One Time |
| OTA | Opitcal Tube Assembly |
| OTC | Overflow of Tacho Counter |
| OUT | Output to Port |
| OUTERNATIONAL | Outside Underestimated Team Restrictions Nationally And Titanium Inside-Outside National Assembly Libary |
| OUTS | Output String to Port |
| OUTSB | Output Byte String to Port |
| OUTSD | Output Doubleword String to Port |
| OUTSW | Output Word String to Port |
| OVF | OverFlow |