- closed ampoule vacuum diffusion
- closed loop
- closed-loop control
- closed-loop frequency response
- closelypacked code
- cloud chamber
- cloverleaf slow wave line
- cluster crystal
- clutter
- clutter map
- CO laser
- co-polarization
- coated powder cathode, CPC
- coaxial antenna
- coaxial cable
- coaxial line
- coaxial magnetron
- coaxial relay
- code
- code block
- code division multiple access, CDMA
- code division multiplexing, CDM
- code generator
- code length
- code rate
- code tree
- code vector
- code word
- code word synchronization
- codebook
- coded transmitter
- codeposition
- coder
- coding theorem
- coercive force
- coevaporation
- coherent grain boundary
- coherent detection
- coherent detector
- coherent optical communication
- coherent pulse radar
- coherent transponder
- cohesion
- coincidence gate
- cold cathode
- cold trap
- cold wall reactor
- cold welding
- collapsing ratio
- collector