| Clifford Smith | Method Man |
| Cliffordalgebra | Clifford algebra |
| Cliffs of Moher | Cliffs of Moher |
| Clifton | Clifton |
| clinch | clinch |
| Clint Eastwood | Clint Eastwood |
| Clinton | Clinton |
| Clinton County | Clinton County |
| Clinton Davisson | Clinton Davisson |
| Clio | Clio |
| Clippertonön | Clipperton Island |
| Clitorism | Clitorism |
| Clive Barker | Clive Barker |
| Clive Burr | Clive Burr |
| Clive Owen | Clive Owen |
| Clive Sinclair | Clive Sinclair |
| Cloaca Maxima | Cloaca Maxima |
| Cloacina | Cloacina |
| Clodius Albinus | Clodius Albinus |
| Clodoaldo | Clodoaldo |
| Cloisonism | Cloisonnism |
| Clonetrooper | Clone troopers |
| Clonmel | Clonmel |
| Clos Lucé | Clos Lucé |
| Close to Home | Close to Home |
| Clotilda | Clotilde |
| Cloud Strife | Cloud Strife |
| Cloudsat | CloudSat |
| Cloviskulturen | Clovis culture |
| clown | clown |
| clowneri | buffoonery |
| clownfisk | clownfish |
| Clowntryckare | Clown triggerfish |
| Club América | Club América |
| Club Atlético Banfield | Club Atlético Banfield |
| Club Atlético de Madrid | Atlético Madrid |
| Club Atlético Independiente | Club Atlético Independiente |
| Club Atlético Lanús | Club Atlético Lanús |
| Club de Deportes La Serena | Club de Deportes La Serena |
| Club de Deportes Puerto Montt | Club de Deportes Puerto Montt |
| Club de Deportes Santiago Wanderers | Club de Deportes Santiago Wanderers |
| Club de Fútbol Monterrey | Club de Fútbol Monterrey |
| Club de Gimnasia y Esgrima La Plata | Club de Gimnasia y Esgrima La Plata |
| Club Deportivo Chivas USA | Club Deportivo Chivas USA |
| Club Deportivo Cruz Azul | Club Deportivo Social y Cultural Cruz Azul |
| Club Deportivo Ferroviario Almirante Arturo Fernández Vial | Club Deportivo Ferroviario Almirante Arturo Fernández Vial |
| Club Deportivo Guadalajara | Club Deportivo Guadalajara |
| Club Deportivo Palestino | Club Deportivo Palestino |
| Club Deportivo San Luis de Quillota | San Luis Quillota |
| Club Deportivo Universidad Católica | Club Deportivo Universidad Católica |
| Club Estudiantes de La Plata | Estudiantes de La Plata |
| Club Nacional de Football | Club Nacional de Football |
| Club Nintendo | Club Nintendo |
| Club Sport Emelec | Club Sport Emelec |
| Club-Cola | Club Cola |
| Clube de Regatas Brasil | Clube de Regatas Brasil |
| Cluedo | Cluedo |
| Clugin | Clugin |
| Cluj | Cluj County |
| Cluj-Napoca | Cluj-Napoca |
| Cluny | Cluny |
| Clyde Tombaugh | Clyde Tombaugh |
| Clydesdale | Clydesdale |
| Clásica de San Sebastián | Clásica de San Sebastián |
| Cláudio Taffarel | Cláudio Taffarel |
| Clémence Poésy | Clémence Poésy |
| Cléo de Mérode | Cléo de Mérode |
| CM Punk | CM Punk |
| CMAS | Confédération Mondiale des Activités Subaquatiques |
| CMDB | CMDB |
| CMOS | CMOS |
| CMTS | Cable modem termination system |
| CMYK | CMYK color model |
| CN | CN |
| CN Tower | CN Tower |
| CNC | CNC |
| CNET | CNET |
| CNG | Compressed natural gas |
| CNIT | Center of New Industries and Technologies |
| CNN | CNN |
| CNR | China Railways |
| CO | CO |
| coach | coach |
| Coachella Valley | Coachella Valley |
| Coachella Valley Music and Arts Festival | Coachella Valley Music and Arts Festival |
| Coahuila | Coahuila |
| Coandaeffekt | Coandă effect |
| Coatlicue | Coatlicue |
| Coba | Coba |
| COBIT | COBIT |
| COBOL | COBOL |
| Cobreloa | Cobreloa |
| Cobresal | Club Deportes Cobresal |
| Coburg | Coburg |
| Coca-Cola | Coca-Cola |
| Coca-Cola BlāK | Coca-Cola BlāK |
| Coca-Cola Company | The Coca-Cola Company |
| Coca-Cola Light | Diet Coke |
| Cochabamba | Cochabamba Department |
| Cochinkina | Cochinchina |
| Cochrane Collaboration | Systematic review |
| Cock Sparrer | Cock Sparrer |
| Cockburn Town | Cockburn Town |
| Cockerpoo | Cockapoo |
| cockerspaniel | cocker spaniel |
| Cockney | Cockney |
| cockpit | cockpit |
| cocktail | cocktail |
| cocktailbar | cocktail lounge |
