- common tangent plane of two spheres
- common variation
- communicating class of states
- communication
- communication
- communication calculus system
- communication channel
- communication network
- communication satellite
- communication sequential process
- communication system
- commutant of operators
- commutative algebra
- commutative Banach algebra
- commutative band
- commutative BCI-algebra
- commutative BCK-algebra
- commutative diagram in a category
- commutative equivalent codes
- commutative equivalent words
- commutative group
- commutative ideal of BCI-algebra
- commutative lattice-ordered group
- commutative law
- commutative law in Boolean algebra