- Classic
- Classical
- Classical antiquity
- Classified
- Clatter
- Clause
- Claustrophobic
- Clavicle
- Clearance sale
- Clearness
- Cleft lip
- Clement
- Cleromancy
- Clever feat
- Clink
- Clip
- Clippers
- Clipping
- Clitoria
- Cloakroom
- Clockwork
- Clod
- Clod hopper
- Cloister
- Clop
- Close around
- Close down
- Clouds
- Clove
- Cloven
- Clownish
- Cloze test
- Club
- Cluck
- Clueless
- Clumsily
- Clumsy
- Clunker
- Clutter
- Coals
- Coals to new castle
- Coast
- Coat of arms
- Coated
- Coattails effect
- Cobalt bomb
- Cobble
- Cobbler
- Cobol
- Cobra
- Cocaine
- Cock
- Codex
- Codger
- Coed
- Coefficient
- Coessential
- Coffee break
- Coffee plant
- Coffer
- Cogitate
- Cogitation
- Cogitative
- Cognate
- Cognisance
- Cold storage
- Cold war
- Cold-blooded
- Cold-hearted
- Coleslaw
- Coliform
- Coliseum
- Colitis
- Collaboratively
- Collage
- Collapse
- Collapsible
- Collar beam
- Collectedly
- Colon
- Colonial
- Colonialism
- Colonization
- Colonize
- Colophon
- Colophony
- Colorectal
- Colour bar
- Colour printing
- Colouring
- Colt
- Come into ones own
- Come out
- Come through
- Come to grief
- Come to his senses
- Commingle
- Coming to blows
- Comma bacillus
- Command-ed