- Circadian rhythm
- Citric acid
- Citronella oil
- City state
- Ciu
- Civet
- Civil case
- Civil engineer
- Civil rights
- Civil service
- Clarion call
- Clarity
- Clash
- Clashing
- Class distinction
- Classicism
- Classroom
- Claustrophobia
- Claviger
- Claw
- Clearly
- Clears
- Cleaver
- Cleft footed
- Clench
- Clenching the fist
- Cleopatra ramases akhnaton tuthankhaman
- Clepsyddra
- Clevage
- Clever person
- Clipper
- Cloaca
- Cloak
- Cloistral
- Close fisted man
- Cloudily
- Cloudiness
- Cloudscape
- Clowder
- Clown
- Cloying
- Clump
- Cluster of lotus blossoms
- Cm
- Coalition
- Coat hanger
- Coaxing
- Cob
- Cobweb
- Cobwebs
- Cock and bull story
- Cock eye
- Codes
- Codification
- Codifier
- Codify
- Codswallop
- Coeliac
- Coenzyme
- Coercion
- Coexisting
- Coffee-table book
- Coffin
- Cogent
- Cognomen
- Cold turkey
- Cold water
- Coldish
- Collaborate
- Collaborative
- Collar bone
- Collate
- Collation
- Colleague
- Colonitis
- Colony
- Colorful
- Colors
- Colossal
- Colostrums
- Colour box
- Colourist
- Colours
- Column
- Columnar
- Com
- Com and go
- Come into force
- Come on
- Come thick and fast
- Come to aid
- Come to an end
- Come to blows
- Come to life
- Come to light
- Coming on
- Comity
- Command
- Commandant
- Commenator