| Abbreviation | Definition |
|---|---|
| OIW | Oregon Iron Works, Inc. |
| OIX | Oregon Internet Exchange |
| OJA | O. J. Advertising, Inc. |
| OJA | O. J. Advertising, Incorporated |
| OJOC | Ojai Oil Company |
| OJSC | Open Joint Stock Company |
| OJSC | Open Joint-Stock Company |
| OJSY | OJsys, Inc. |
| OK | Orville Knoxville |
| OKB | Outrigger Kauai Beach Hotel & Conference Center |
| OKC | Ontario Knife Company |
| OKF | Ox Kill Farm |
| OKG | O'Neill, Kellner, & Green |
| OKG | Oskarshamns KraftGrupp AB |
| OKM | Ortungstechnik Krauss & Mueller |
| OKN | Oakton Computing Limited |
| OKN | Olugbala Kokumo Network |
| OKR | OutKast Racing |
| OKS | Fachgebiet Offene KommunikationsSysteme |
| OKS | Otnar Kaucuk Sanayi |