China 
Africa 
- Custody transfer
- Custom software
- Customer analytics
- Customer edge router
- Customer equity
- Customer experience
- Customer knowledge
- Customer service
- Cut
- Cut and fill
- Cut point
- Cut-off
- Cutaneous leishmaniasis
- Cuticle
- Cutin
- Cutinase
- Cutis
- Cutoff
- Cutoff frequency
- Cutoff grade
- Cutoff voltage
- Cutter location
- Cutting
- Cutting fluid
- Cutting stock problem
- Cutting tools
- Cutting-plane method
- Cutwater
- Cuvettes
- Cwt
- Cyanamide
- Cyanate
- Cyanate ester
- Cyanation
- Cyanide
- Cyanine
- Cyano radical
- Cyanoacrylate
- Cyanobacteria
- Cyanocobalamin
- Cyanoethylation
- Cyanogen
- Cyanogen bromide
- Cyanogen chloride
- Cyanohydrins
- Cyanophycin
- Cyanosis
- Cyanotoxins
- Cyanuric acid
- Cyanuric chloride
- Cyber insurance
- Cyber manufacturing
- Cyber resilience
- Cyber spying
- Cyber-physical system
- Cyberattack
- Cyberbullying
- Cybercrime
- Cyberinfrastructure
- Cybernetics
- Cybersecurity
- Cyberstalking
- Cyberterrorism
- Cyberwarfare
- Cyborgs
- Cyc
- Cyclam
- Cyclamate
- Cycle basis
- Cycle detection
- Cycle graph
- Cycle index
- Cycle of erosion
- Cycle per second
- Cycle track
- Cycler
- Cyclic
- Cyclic adenosine monophosphate
- Cyclic codes
- Cyclic compound
- Cyclic di-gmp
- Cyclic executive
- Cyclic group
- Cyclic guanosine monophosphate
- Cyclic nucleotides
- Cyclic olefin copolymer
- Cyclic order
- Cyclic peptides
- Cyclic permutation
- Cyclic prefix
- Cyclic stress
- Cyclic voltammetry
- Cyclin
- Cyclin A
- Cyclin B
- Cyclin E
- Cycling
- Cycling infrastructure
- Cycloaddition
- Cycloalkanes
- Cycloalkenes
- Cyclobutadiene
- Cyclobutane
- Cycloconverter
- Cyclodextrin
- Cyclodextrin glycosyltransferase
- Cycloheptane
- Cycloheptatriene
- Cyclohexane
- Cyclohexanecarboxylic acid
- Cyclohexanedimethanol
- Cyclohexanol
- Cyclohexanone
- Cyclohexanone oxime
- Cyclohexene
- Cyclohexene oxide
- Cyclohexylbenzene
- Cycloid gear
- Cycloids
- Cycloisomerization
- Cyclomatic complexity
- Cyclone
- Cyclone furnace
- Cyclooctadiene
- Cyclooctatetraene
- Cyclooctene
- Cyclooxygenase
- Cycloparaphenylene
- Cyclopentadiene
- Cyclopentadienyl radical
- Cyclopentane
- Cyclopentanol
- Cyclopentanone
- Cyclopentene
- Cyclopentenone
- Cyclopentyl methyl ether
- Cyclophane
- Cyclophosphamide
- Cycloplegia
- Cyclopropanation
- Cycloserine
- Cyclothems
- Cyclotides
- Cyclotron frequency
- Cyclotron radiation
- Cyclotron resonance
- Cyclotrons
- Cyfluthrin
- Cygwin
- Cylinder