| Abbreviation | Definition |
|---|---|
| OHT | OverHead Transparency |
| OHV | OverHead Viewer |
| OIR | Online Insert and Removal |
| OIS | Open Interconnected System |
| OIT | Operator Interface Terminal |
| OLTE | Optical Line Termination Equipment |
| OLTT | Open Loop Thermal Throttling |
| OMER | Optical Music Easy Reader |
| OMR | Optical Music Recognition |
| OMS | Outage Management System |
| ON-PREM | on-premises |
| ONT | Optical Network Terminal |
| ONU | Optical Node Unit |
| OOD | Other Output Drive |
| OOO | Out Of Order |
| OOOF | Out-Of-Order-Frame |
| OOPS | Out Of Paper Sensor |
| OP | Open Platform |
| OP | Open Plug |
| OPAC | Optimization Policies for Adaptive Control |