China 
Africa 
- Cluster randomized trial
- Clusterin
- Clustering algorithms
- Clusters of differentiation
- Cluttering
- Cmin
- Co oximeter
- Co-dydramol
- Co-option
- Co-oximetry
- Co-receptors
- Co-rumination
- Co-sleeping
- Co-stimulation
- Coacervates
- Coacervation
- Coaching psychology
- Coactivation
- Coagulant
- Coagulase
- Coagulase negative staphylococci
- Coagulase negative staphylococcus
- Coagulase positive staphylococci
- Coagulation
- Coagulation cascade
- Coagulation factor IX
- Coagulation factor VII
- Coagulation factor VIII
- Coagulation factor X
- Coagulation factor XI
- Coagulation factor XII
- Coagulation factor XIII
- Coagulation screen
- Coagulation system
- Coagulation testing
- Coagulative necrosis
- Coagulin
- Coagulopathies
- Coagulopathy
- Coal dust
- Coal gas
- Coal oil
- Coal tar
- Coalescence
- Coarctation of the aorta
- Coarse facial features
- Coarticulation
- Coats' disease
- Cobalamin
- Cobalt
- Cobalt 60
- Cobalt sulfate
- Cobalt-60
- Cobalt-chrome
- Cobamamide
- Cobb angle
- Cobblestone lissencephaly
- Cobimetinib
- Cobratoxin
- Coca
- Coca tea
- Cocaethylene
- Cocaine
- Cocaine and amphetamine regulated transcript
- Cocaine dependence
- Cocaine hydrochloride
- Cocaine intoxication
- Cocaine overdose
- Cocaine- and amphetamine-regulated transcript
- Cocaine-related disorders
- Cocamide
- Cocamidopropyl betaine
- Cocarcinogen
- Cocci
- Coccidia
- Coccidioides immitis
- Coccidioides posadasii
- Coccidioidin
- Coccidioidomycosis
- Coccidiosis
- Coccidiostats
- Coccobacillus
- Coccydynia
- Coccygeal plexus
- Coccygectomy
- Coccygeus muscle
- Coccyx
- Cochineal
- Cochlear
- Cochlear amplifier
- Cochlear aqueduct
- Cochlear duct
- Cochlear implant
- Cochlear implantation
- Cochlear nerve
- Cochlear nucleus
- Cochlin
- Cochliomyia hominivorax
- Cochran's Q test
- Cochrane Collaboration
- Cochrane Library
- Cockayne syndrome
- Cocktail party effect
- Cocoa
- Cocoa beans
- Cocoa butter
- Cocodamol
- Coconut
- Coconut oil
- Cocooning
- Cocos nucifera
- Cocoyam
- Coculture
- Cod liver oil
- Codeine
- Codeine phosphate
- Codeinone
- Codependency
- Codex Alimentarius
- Coding DNA
- Coding region
- Coding strand
- Codominance
- Codon
- Codon reassignment
- Codon usage
- Codrug
- Coefficient of determination
- Coefficient of variation
- Coelenteramide
- Coelenterazine
- Coeliac disease
- Coelom
- Coelomocytes
- Coenocytes
- Coenzyme A
- Coenzyme Q10 deficiency
- Coenzyme q10
- Coenzymes
- Coercion
- Coevolution
- Coexistence
- Cofactors
- Coffea
- Coffee
- Coffee ground vomiting
- Coffin-Lowry Syndrome
- Coffin-Lowry syndrome
- Coffin-Siris syndrome
- Cofilin