- Classic
- Classical
- Classical antiquity
- Classified
- Clatter
- Clause
- Claustrophobic
- Clavicle
- Clay
- Clean down
- Clean from
- Clean hands
- Clean-handed
- Clean-shaven
- Cleanliness
- Cleanness
- Clearance sale
- Clearness
- Cleft lip
- Clement
- Cleromancy
- Clever feat
- Cleverness
- Cliff
- Climbers
- Climbing plant
- Climbing stem
- Clinging
- Clinging steadfastedly on
- Clinical psychology
- Clink
- Clip
- Clippers
- Clipping
- Clitoria
- Cloakroom
- Clockwork
- Clod
- Clod hopper
- Cloister
- Clop
- Close around
- Close down
- Close with
- Close-knit
- Closeted
- Closing
- Closing the eyes
- Closure
- Clothes
- Clothesline
- Clothing
- Cloud nine
- Clouds
- Clove
- Cloven
- Clownish
- Cloze test
- Club
- Cluck
- Clueless
- Clumsily
- Clumsy
- Clunker
- Clutter
- Cmos
- Co-education
- Co-heir
- Co-opt
- Co-respondent
- Co-star
- Co-worker
- Coach
- Coach load
- Coagulate
- Coalgate
- Coals
- Coals to new castle
- Coast
- Coat of arms
- Coated
- Coattails effect
- Cobalt bomb
- Cobble
- Cobbler
- Cobol
- Cobra
- Cocaine
- Cock
- Cockalarum
- Cockscomb
- Cocksure
- Cocktail
- Coco
- Coconut
- Cocopeat
- Coddle
- Code
- Codex
- Codger