| Abbreviation | Definition |
|---|---|
| OFN | Old F***ing News |
| OFN | Old Fucking News |
| OGN | Oil Gas News |
| OGN | Old Guard News |
| OGN | On The Ground News |
| OHP | Open Humanities Press |
| OIDMTC | Ontario Interactive Digital Media Tax Credit |
| OINP | Over Issued News Papers |
| OIS | Oakcrest Intermediate School |
| OITN | Occoquan In the News |
| OLA | Operational Level Agreement |
| OLBIN | Optical Long Baseline Interferometry News (NASA forum) |
| OLN | Off Licence News |
| OLTL | One Life To Live |
| OMDC | ONT Media Dvlpt Corp |
| OMM | Obsolete Media Miami |
| OMP | Open Monograph Press |
| ONA | Oman News Agency |
| ONA | Omogeneia News Agency |
| ONA | Online News Assn |