a person, country, etc, that signs a document jointly with others
adjective
2.
signing jointly with another or others
cosigner in American English
(ˈkouˌsainər, kouˈsai-)
noun
1.
a cosignatory
2.
a joint signer of a negotiable instrument, esp. a promissory note
Word origin
[1900–05; co- + signer]This word is first recorded in the period 1900–05. Other words that entered Englishat around the same time include: cathode-ray tube, decompression, hormone, hydroplane, throwawayco- is a prefix meaning “with,” “together,” “in association,” sometimes with the derivedsense “auxiliary, subsidiary” (coenzyme; copilot), and, in mathematics and astronomy, with the sense “complement” (codeclination)