- counter-sill
- counteraction
- counterbracing
- countercheck
- countercurrent
- countercurrent classifier
- counterelectromotive force
- counterflort
- counterflow
- counterfort
- counterfort dam
- counterpoise
- counterpressure
- countershaft
- countershaft axle
- countershafting
- countersink bit
- countersunk bolt
- countersunk hole
- countersunk rivet
- countersunk setting
- counting
- counting device
- counting machine
- counting rate
- counting relay
- counting tube
- countless
- country
- countryside
- couplant film
- couple column
- couple roof
- coupled circuit
- coupled pipe
- coupler
- coupling
- coupling agent
- coupling bolt
- coupling box
- coupling capacitor
- coupling coefficient
- coupling coil
- coupling device
- coupling element
- coupling hole
- coupling joint
- coupling loop
- coupling network
- coupling nut
- coupling rod
- coupling slot
- courage
- course analysis
- courseware
- courteous
- courtesy copy
- courtesy light
- courtier
- couveuse
- covalent
- covalent bond
- cove
- coved wire
- covenant
- cover
- cover coat
- cover disk
- cover gas
- cover grate
- cover hood
- cover material
- cover sheet
- cover slab
- coverage
- coverage area
- coverage overlap
- covered
- covered backing
- covered drain
- covered electrode
- covered market
- covered yarn
- covering capacity
- covering layer
- covering paint
- covering slate
- coverstrip
- cowl
- cown mold
- coxswain
- CPT theorem
- CPU time
- crab angle
- crack
- crack detector
- crack formation
- crack ice
- crack resistance
- cracked