| Abbreviation | Definition |
|---|---|
| OCI | Organization of the Islamic Conference |
| OCIC | Order of Christian Initiation for Children |
| OCIC | Orthodox Christian Information Center |
| OCJ | Orthodox Church in Japan |
| OCL | Orthodox Christian Laity |
| OCL | Orthodox Christian Laity Orthodox Christian Laity |
| OCM | Ocean Chinese Mission |
| OCM | One Click Ministry |
| OCMB | Operation Clambake Message Board |
| OCN | Orthodox Christian Network |
| OCP | Oregon Catholic Press |
| OCPM | Orthodox Christian Prison Ministry |
| OCRT | Ontario Consultants on Religious Tolerance |
| OCS | Oklahoma Christian School |
| OCS | Omaha Catholic Schools |
| OCS | Only Christ Saves |
| OCS | Ouachita Christian School |
| OCS | Ouachita Christian Schools |
| OCSA | Orthodox Christian Scout Association |
| OCSB | Ottawa Catholic School Board |