| Abbreviation | Definition |
|---|---|
| NWFA | National Women's Football Association |
| NWFA | North Western Football Association |
| NWFU | North West Football Union |
| NYCFC | New York City Football Club |
| NYFA | National Youth Football Alliance |
| NYPFL | New York Pro Football League |
| NZFC | New Zealand Football Championship |
| NZRFU | New Zealand Rugby Football Union |
| OAFA | Orkney Amateur Football Association |
| OAFC | Ormond Amateur Football Club |
| OAFO | Ohio Association Of Football Officials |
| ODFL | Omeo & District Football League (Australia) |
| OFA | Oregon Football Association |
| ÖFB | Österreichischer Fußball-Bund |
| OFC | Oceania Football Confederation |
| OFC | Ontario Football Conference |
| OFFL | Online Fantasy Football League |
| OFL | Official Football League (Fantasy Football) |
| OFL | Off-season Football League |
| OFM | Online Football Manager |