co-sign
UK[ˌkəʊˈsaɪn]US[ˌkoʊˈsaɪn]
v
To sign a document jointly with another person, especially in order to accept legal responsibility for a debt or obligation if the other person fails to pay.
v
To endorse or support a statement, idea, or person publicly.
Morpheme Breakdown
co
sign
co
together
sign
write one's name
Etymology
The word 'cosign' is a modern English formation, directly combining the Latin-derived prefix 'co-' with the verb 'sign'. The prefix 'co-', a variant of 'com-', originates from the Proto-Indo-European root kom, meaning 'beside' or 'near', which in Latin evolved to signify accompaniment and joint action. The base 'sign' descends from Latin 'signum', a term for a distinguishing mark or seal, itself of uncertain but possibly Etruscan origin. The literal compounding of these elements—'to sign together'—perfectly captures the word's core legal and social functions: the shared act of endorsing a document to share liability or the joint act of publicly supporting a cause or individual.
Analysis
Structure: co (together) + sign (write one's name)
- co: A prefix from Latin 'com-', meaning 'together', 'with', or 'jointly'. In this word, it indicates joint action.
- sign: From Latin 'signum', meaning 'mark', 'token', or 'seal'. In this word, it functions as the base verb meaning to write one's name as a formal endorsement.
Examples
The bank required her father to cosign the loan application.
Several prominent scientists cosigned the open letter calling for climate action.
If you cosign for a friend's apartment lease, you are equally responsible for the rent.