| Abbreviation | Definition |
|---|---|
| OCCD | Ohio Conference of Community Development |
| OCI | Office of Conferences Institutes |
| OCLC | Organic Commodities and Livestock Conference |
| OCLU | Ottawa Conference for Linguistics Undergraduates |
| OCMC | Organizational Communication Mini Conference |
| OCMG | Orlando Conference Management Group |
| OCPP | Ohio Conference for Payroll Professionals |
| OCS | Online Conference Service |
| ODAC | Old Dominion Athletic Conference |
| ODATA | Working Symposium on Oceanographic DATA Systems |
| ODBE | Open Designers and Buyers Event |
| ODC | Operational Development Conference |
| ODS | Topical Meeting on Optical Data Storage |
| ODSC | Open Data Science Conference |
| OECC | Opto Electronics And Communications Conference |
| OEMC | Ontario East Municipal Conference |
| OETC | Ohio Educational Technology Conference |
| OFC | Conference on Optical Fiber Communication |
| OFC | Ontario Football Conference |
| OFC | Optical Fiber Communication Conference and Exposition |