| Abbreviation | Definition |
|---|---|
| CIO | Congress of Industrial Organizations |
| CIP | Canadian Institute of Planners |
| CIP | Colegio de Ingenieros del Peru (College of Engineers of Peru) |
| CIPA | Canadian International Pharmacy Association |
| CIPA | Chartered Institute of Patent Agents |
| CIPA | Colorado Independent Publishers Association |
| CIPA | Cultural Ink Press Association |
| CIP-ICU | Canadian Institute of Planners/Institut Canadien des urbanistes |
| CIPSOCIETY | Chartered Insurance Professionals' Society (Canada) |
| CIRA | Canadian Industrial Relations Association |
| CIRB | Consortium of Independent Review Boards |
| CIRB | Construction Industry Research Board |
| CIRC | Centre international de recherche sur le cancer |
| CIRCLE | Circle and Instruction Resource Center Linking Educators |
| CIRF | Chronic Illness Relief Fund |
| CISA | Casting Industry Suppliers Association |
| CISA | Computer and Information Science Association |
| CISC | Chicago Interactive Social Club |
| CISC | Creative Industry Skills Council |
| CISC | CRTC Interconnection Steering Committee |