| Abbreviation | Definition |
|---|---|
| CMWS | Connie Mack World Series |
| CNAH | Canadian National Aboriginal Hockey Tournament |
| CNAHT | Canadian National Aboriginal Hockey Tournament |
| CNBA | Commission Nationale de Boxe Amateur |
| CNDCC | Chipping Norton and District Cricket Club |
| CNSD | Colts Neck School District |
| CNSM | Clube N??utico de Salvaterra de Magos |
| CNVTM | Campionatul National de Viteza pe Traseu Montan |
| CNW | Canadian National Winner |
| COA | Challenged Outdoorsmen of America |
| COA | Cheerleaders Of America |
| COACH | Comprehensive Online Access to Coaching Help |
| COBA | Central Ontario Badminton Association |
| COBA | Central Ontario Baseball Association |
| COBA | Council of Black Administrators |
| COBRA | Combined Old Boys Rugby Association |
| COC | Canadian Olympic Committee |
| COC | Champions Of Champions |
| COC | Clerk Of the Course |
| COC | Cleveland Open Cup |