- circlip
- circuit board
- circuit commutation
- circuit switching
- circular flow
- circular functions
- circular line
- circular route
- circular scale
- circular sewer
- circular shift
- circular slot
- circular stairs
- circular table
- circular track
- circulating
- circulating capital
- circulating decimal
- circulating fan
- circulating storage
- circulating water
- circulation brine
- circulation loop
- circulation method
- circulation oiling
- circulation pump
- circulation system
- circulation traffic
- circulation water
- circulator
- circulatory system
- circum
- circumambient medium
- circumference
- circumferential fault
- circumferential seam
- circumflex
- circumflexus
- circumrenal
- cirium
- city planning
- city water
- civil architect
- civil engineering
- clack valve
- cladding
- circulating system
- circulation lubrication
- circulator pump
- circulus
- circumferential road
- circumferential stress
- circumflex symbol
- circumfluent
- cistern
- cisterna
- citation
- city gas
- civil engineer
- CLA height
- clack mill
- cladding layer
- cladiosis
- clam pack
- clamminess
- clamp check
- clamp ring
- clamped guided
- clamper
- clamping die
- clamping handle
- clamping nut
- clamping screw
- clamping strap
- clamps
- clan
- Clapeyron equation
- clapper valve
- clarified water
- clarifier-digester
- clarifying basin
- clashing
- clasp nail
- class descriptor
- class object
- classification chart
- classification table
- classroom
- clastic
- clastic limestone
- clause
- claw
- claw coupling
- clay conduit
- clay grouting
- clay kneader
- clay marl
- clay mixer
- clay pan
- clay press