- circlet
- circuit analysis
- circuit breaker
- circuit capacitance
- circuit group
- circuit layout
- circuit topology
- circular aperture
- circular buoy
- circular channel
- circular file
- circular frequency
- circular matrix
- circular polling
- circular saw
- circularly-polarized
- circulate
- circulating assets
- circulating coolant
- circulating memory
- circulating pump
- circulation
- circulation flow
- circumferential
- circumferential edge
- circumferential sapce
- circumferential speed
- circumferential velocity
- circumrotate
- circumscribe
- circumscribed circle
- circumstance
- circus
- cirque
- cistern barometer
- citadel
- citizen
- city
- city block
- city district
- city gate
- city line
- city map
- city zone
- civil
- civil architecture
- civil construction
- civil law
- civilian construction
- civilization
- clack
- clad
- cladding material
- cladding sheet
- claim
- claim license
- clammy
- clamp screw
- clamped
- clamping
- clamping bolt
- clamping circuit
- clamping device
- clamping diode
- clamping force
- clamping mechanism
- clamping plate
- clamping pulses
- clamping ring
- clamping sleeve
- clamping stirrup
- clamping stud
- clamping tube
- clamshell bucket
- clamshell crane
- clamshell grab
- clap sill
- clapper box
- clarification basin
- clarifier
- clarify
- clarifying agent
- clarifying filter
- clarifying tank
- clasp clarifier
- class
- class function
- class interval
- class limit
- class number
- classcification
- classic architecture
- classical architecture
- classical concept
- classicism
- classification
- classification system
- classification yard
- classifier
- classify