| Acronym | Definition |
|---|
| C4 | Command, Control, Communications, and Computers (US DoD) |
| C4 | Composition 4 (explosive) |
| C4 | Channel 4 (UK Terrestrial Television) |
| C4 | Carrera 4 (Porsche 911 model) |
| C4 | Butane |
| C4 | Middle C (piano keyboard) |
| C4 | Combat Casualty Care Course |
| C4 | Schedule IV Controlled Substance (USA) |
| C4 | Chaos Computer Club Cologne (German computer club in Cologne member of the CCC family) |
| C4 | Center for Clouds, Chemistry and Climate |
| C4 | Fourth-Generation Corvette (Chevrolet) |
| C4 | Trident I Missile |
| C4 | Controlled Collapse Chip Connect |
| C4 | Controlled Collapsed Chip Connection |
| C4 | Call Centre Consulting Connection (Canada) |
| C4 | Central CONUS Control Center (GPS) |
| C4 | Care, Competence, Control and Communications (Teksystems project management methodology) |