China 
Africa 
- Costate equations
- Costimulatory
- Costovertebral joint
- Costovertebral joints
- Cotangent bundle
- Cotinine
- Cotton
- Cotton candy
- Cotton gin
- Cotton mills
- Cotton pad
- Cotton wool spots
- Cottrell atmosphere
- CouchDB
- Couette flow
- Cough
- Cough reflex
- Coulees
- Coulomb barrier
- Coulomb blockade
- Coulomb collision
- Coulomb damping
- Coulomb explosion
- Coulombic efficiency
- Coulometry
- Coulter
- Coulter counter
- Coumarin
- Coumarins
- Coumestrol
- Count data
- Countable set
- Countably additive
- Countdown
- Counter
- Counter-electromotive force
- Counterbore
- Countercurrent distribution
- Counterions
- Countermeasures
- Counterpoise
- Counterregulatory hormones
- Countersink
- Counterstain
- Counterweights
- Counting
- Counting efficiency
- Counting measure
- Country rock
- Coupled mode theory
- Couplers
- Couples
- Coupling
- Coupling constant
- Coupling loss
- Coupling reactions
- Covalent bond
- Covalent radius
- Covariance
- Covariance and correlation
- Covariance function
- Covariance intersection
- Covariance matrix
- Covariantly
- Cove
- Covellite
- Cover
- Cover crops
- Cover meter
- Coverage
- Coverage probability
- Covering number
- Covering problem
- Covering problems
- Covert channels
- Cow dung
- Cowl
- Cowling
- Cowpea
- Cowpea mosaic virus
- Cowpox
- Coxa vara
- Coxiella burnetii
- Coxsackievirus
- Cp
- CpG sites
- Cplex
- Cr(CO)6
- Crabtree effect
- Crack closure
- Crack growth resistance curve
- Crack tip opening displacement
- Cracking
- Crackles
- Cradle
- Cradle-to-cradle design
- Craft production
- Craftsmanship
- Craigslist
- Cramer's rule
- Cramps
- Crane
- Cranial cavity
- Cranial nerve
- Cranial vault
- Craniectomy
- Craniofacial
- Craniofacial surgery
- Craniotomy
- Crank
- Crankcase
- Crankcase dilution
- Crankcase heater
- Crankcase ventilation system
- Crankpin
- Crankset
- Crankshaft
- Crash
- Crash test
- Crate
- Crater Lake
- Craters
- Cratons
- Crawl space
- Crawler
- Cray XK7
- Cray-2
- Crazing
- Cream
- Creaming
- Creatinase
- Creatine
- Creatine kinase
- Creatinine
- Creation and annihilation operators
- Creative problem solving
- Creative problem-solving
- Creativity
- Creativity techniques
- Credible intervals
- Credit ratings
- Credit risk
- Creep
- Creeping waves
- Cremophor EL
- Crenulation
- Creo
- Creosote
- Cresol
- Crevasse splay