| Abbreviation | Definition |
|---|---|
| OBSL | Old Bridge Soccer League |
| OBSL | Olney Bethesda Soccer League |
| OCSA | Onslow Classic Soccer Association |
| ODSC | Old Dominion Soccer Club |
| ODSL | Old Dominion Soccer League |
| OFI | Omilos Filathlon Irakliou (Greek soccer team) |
| OJSC | Onslow Junior Soccer Club |
| OMSA | Okotoks Minor Soccer Association |
| OMSA | Old Mans Soccer Association |
| OOSL | Orion Oxford Soccer League |
| OPSC | Overland Park Soccer Club |
| OPSL | Oregon Premier Soccer League |
| OSA | Oklahoma Soccer Association |
| OSA | Online Soccer Academy |
| OSA | Ontario Soccer Association |
| OSA | Outdoor Soccer of America |
| OSF | Our Soccer Field |
| OSL | Ontario Soccer League |
| OSM | Online Soccer Manager |
| OWSL | Ontario Women's Soccer League |