| Abbreviation | Definition |
|---|---|
| CRU | Classification Review Unit |
| CRV | Conditional Release Violator |
| CS | Confidential Source |
| CSC | Civil Service Commission |
| CSIS | Canadian Security Intelligence Service |
| CSLPO | Corruption of State and Local Public Officials |
| CTA | Control Terminal Agency |
| CTNF | Computerized Telephone Number File |
| CTRD | Covert Telephone Recording Device |
| CV | Cleveland Field Office |
| DAF | DNA Amplification Fingerprinting |
| DAPLI | Department APpLIcant |
| DC | Detention of Communists |
| DCGO | District Coast Guard Office |
| DCI | Director of Central Intelligence |
| DCOC | Department for Combating Organized Crime |
| DCS | Domestic Contact Service of the CIA |
| DDI | Dangerous Drug Informant |
| DDR | Dynamic Data Reconstruction |
| DE | Detroit Field Office |