To sign a document jointly with another person, sometimes as an endorsement. / (slang) To agree with or endorse

The promotion of one musical artist (usually less successful) by another.

A cosignatory / (law) A person who accepts joint responsibility for the debt of another

plural of cosigner

Third-person singular simple present indicative form of cosign

simple past tense and past participle of cosign

present participle of cosign

(biology) Any of a group of coordinated signals

signed or signing jointly

Any of several people who sign a document together (especially a treaty)