co-
Alongside, with another
Co- is a prefix meaning together, jointly, or mutually.
It attaches to nouns and verbs to indicate partnership or shared status: co-author, co-pilot, co-sign, co-founder.
The hyphen is standard after co- when the base word begins with a vowel or to prevent misreading, though usage varies: cooperate and co-operate are both common.
Work jointly with others
- coordinateArrange for unified action
- coauthorJoint creator of text
- cofounderJoint business originator
- coworkerFellow employee
copilot · costar · cohost · cocreate · cochair · coproducer · codevelop · codesign
Live together harmoniously
- coincideOccur together in time
- contemporaneousExisting at same time
- concurrentHappening at once
- coevalSame age or period
coordinate · synchronous · parallel · concomitant · coterminous · alongside · overlapping · coincident
Auxiliary aircraft operator
- copassengerOne traveling alongside you
- codriverRacing navigator assistant
- companionOne who keeps company
- escortOne who accompanies another
alongside · attendant · adjunct · auxiliary · secondary · supporting · supplementary · accessory
Having identical rank
- coprincipalShared top administrator
- coheirOne sharing an inheritance
- coordinateArrange for unified action
- peerOne of similar standing
partner · counterpart · fellow · mutual · reciprocal · balanced · equivalent · parity
cooperate
Work jointly with others
- coordinateArrange for unified action
- coauthorJoint creator of text
- cofounderJoint business originator
coworker · copilot · costar · cohost · cocreate · cochair · coproducer · codevelop · codesign · comanage
coexist
Live together harmoniously
- coincideOccur together in time
- contemporaneousExisting at same time
- concurrentHappening at once
coeval · coordinate · synchronous · parallel · concomitant · coterminous · alongside · overlapping · coincident · simultaneous
copilot
Auxiliary aircraft operator
- copassengerOne traveling alongside you
- codriverRacing navigator assistant
- companionOne who keeps company
escort · alongside · attendant · adjunct · auxiliary · secondary · supporting · supplementary · accessory
coequal
Having identical rank
- coprincipalShared top administrator
- coheirOne sharing an inheritance
- coordinateArrange for unified action
peer · partner · counterpart · fellow · mutual · reciprocal · balanced · equivalent · parity · codependent