| Acronym | Definition |
|---|
| C3 | Propane |
| C3 | Colorectal Cancer Coalition (Alexandria, Virginia) |
| C3 | Command, Control, and Communications (US DoD) |
| C3 | College, Career, and Civic Life (education) |
| C3 | Composition 3 (explosive) |
| C3 | Consultation, Command and Control (NATO) |
| C3 | Capability 3 |
| C3 | Communicatie Centrum Chemie (Dutch: Chemistry Communication Center; Netherlands) |
| C3 | Clarity 3 (Everquest game) |
| C3 | Cambridge Community Church |
| C3 | Consultation, Command & Control |
| C3 | Community Centred Conservation (UK) |
| C3 | Schedule III Controlled Substance (USA) |
| C3 | Career Captains Course (US Army) |
| C3 | Ceramic Cased Capacitor |
| C3 | CPU State 3 (normal sleep mode, computing) |