| Abbreviation | Definition |
|---|---|
| CIRC | Computer Information Resource Center |
| CIRS | Center Information Retrieval System (CDRH) |
| CIS | Central Intelligence Services |
| CIS | Construction Industry Scheme |
| CIS | Consumer Information Statement |
| CIS | Criminal Investigation Section |
| CIS | Customs Information System |
| CISAC | Committee on International Security and Arms Control |
| CISADA | Comprehensive Iran Sanctions, Accountability, and Divestment Act |
| CIT | Center for Information Technology (NIH) |
| CIT | Citizen |
| CITA | Committee for the Implementation of Textile Agreements |
| CITL | Center for Information Technology Leadership |
| CITM | Conversion Internal Tech Memo |
| CJ | Chief Justice |
| CL | Compliance Letter |
| CL | Congressional Library |
| CLEAR | clinical, leadership, educational, administrative and research productivity |
| CLHR | Committee on Labor and Human Resources |
| CLIA | Clinical Laboratory Improvements Act |