China 
Africa 
- Childhood leukemia
- Chill casting
- Chilled beams
- Chilled water
- Chillers
- Chills
- Chimeras
- Chimneys
- Chinese Postman Problem
- Chinese Remainder Theorem
- Chinese Room
- Chinese restaurant process
- Chinese train control system
- Chip formation
- Chip log
- Chiplets
- Chips
- Chipseal
- Chipset
- Chiral
- Chiral drugs
- Chiral media
- Chiral phosphoric acid
- Chiral symmetry
- Chirality
- Chiropractic
- Chirp
- Chirp spread spectrum
- Chirped pulse amplification
- Chirplet transform
- Chisel
- Chitin
- Chitin deacetylase
- Chitin synthase
- Chitinase
- Chitobiose
- Chitosan
- Chlamydia
- Chlamydia psittaci
- Chlamydomonas reinhardtii
- Chloral
- Chloralkali process
- Chlorambucil
- Chloraminated
- Chloramination
- Chloramine-t
- Chloramines
- Chloramphenicol
- Chlorate
- Chlordane
- Chlorella vulgaris
- Chlorhexidine
- Chloride
- Chloride cells
- Chloride channels
- Chloride process
- Chlorin
- Chlorinated aromatic hydrocarbons
- Chlorinated paraffins
- Chlorinated polyethylene
- Chlorinated polyvinyl chloride
- Chlorination
- Chlorine
- Chlorine dioxide
- Chlorine fluoride
- Chlorine trifluoride
- Chlorine-36
- Chlorite
- Chlorite group
- Chlornaphazine
- Chloro-m-cresol
- Chloroacetaldehyde
- Chloroacetic acid
- Chloroauric acid
- Chlorobenzene
- Chlorodifluoromethane
- Chloroethane
- Chloroethylene oxide
- Chloroflexus aurantiacus
- Chlorofluorocarbons
- Chloroform
- Chloroformate
- Chlorogenic acid
- Chloromethane
- Chloromethyl methyl ether
- Chloroperoxidase
- Chlorophenol
- Chlorophyll
- Chlorophyll a
- Chlorophyll b
- Chlorophyll fluorescence
- Chlorophyllin
- Chloroplast DNA
- Chloroplatinic acid
- Chloroprene
- Chlorothalonil
- Chlorotoluene
- Chlorotoxin
- Chlorotrifluoromethane
- Chlorous acid
- Chlorpromazine
- Chlorpropamide
- Chlorpyrifos
- Chlortetracycline
- Chocks
- Chocolate
- Chocolate agar
- Choice architecture
- Choice modelling
- Choices
- Choke valve
- Choked flow
- Choking
- Cholangiocarcinoma
- Cholangitis
- Cholecalciferol
- Cholecystectomy
- Cholecystitis
- Cholecystokinin
- Choledocholithiasis
- Cholera
- Cholera toxin
- Cholesky decomposition
- Cholestanol
- Cholestasis
- Cholesteric
- Cholesteric liquid crystal
- Cholesterol
- Cholesterol oxidase
- Cholesteryl esters
- Cholestyramine
- Cholic acid
- Choline
- Choline acetyltransferase
- Choline chloride
- Choline kinase
- Choline oxidase
- Choline transporter
- Cholinergic
- Cholinergic crisis
- Cholinergic neurons
- Cholinesterase
- Cholinesterase inhibitors
- Chomsky hierarchy
- Chondroblasts
- Chondrocytes
- Chondroitin
- Chondroitin sulfate
- Chondroplasty
- Chondroprotective