| Abbreviation | Definition |
|---|---|
| NYNC | New York Numismatic Club |
| NYSC | New York Soccer Club |
| NZAC | New Zealand Alpine Club |
| NZCC | New Zealand Computer Club |
| NZCC | New Zealand Computer Club Inc |
| NZKC | New Zealand Kennel Club |
| OAAC | Ozarks Amateur Astronomers Club |
| OABC | Ontario Association of Beagle Clubs |
| OAC | Odyssey Adventure Club |
| OAC | Olympic Athletic Club |
| OAC | On Athletics Club |
| OACC | Orange Apple Computer Club |
| OAFC | Oldham Athletic Football Club |
| OAFC | Ormond Amateur Football Club |
| OAK | Organisation of Aberdeen Kirks |
| OBC | Occoquan Boat Club |
| OBC | Ohio Basketball Club |
| OBC | Oriental Basketball Club |
| OBC | Outboard Boating Club |
| OBC | Outrageous Builders Club |