共

party line (telephone line shared by multiple subscribers)

synchronic

the Communist camp

Computing

common area

Common noun

equality (e.g. gender); joint participation

Nouns which may take the genitive case particle 'no'

multi-agency

Economics

tragedy of the commons

Computing

common factor

sound box (of an instrument); sounding box

common first-stage (university entrance) examination

joint struggle

Economics

public value; shared value

collective farm

growing together; joint development

Mathematics

covariance; covariant

Law

criminal conspiracy (participation in the planning of a crime, but not its execution)

Communist China

joint manufacturing; joint production; production joint venture

joint work (art, music, etc.)

communist cell

code-sharing (e.g. airlines); joint operation

Computing

symmetric key cryptography

Computing

shared memory

Computing

shared disk

joint management