co-signer

IPA/ˌkəʊˈsaɪ.nər/
IPA/ˈkoʊˌsaɪ.nɚ/

co-signer — noun

1. a person who signs a loan or rental agreement together with the main applicant,

1.nounB2
Definition

a person who signs a loan or rental agreement together with the main applicant, agreeing to take over payments if that person fails to pay

Example

Without a co-signer, the bank would not approve Yuki's student loan application.

co-signer + of + [document]: who guarantees repayment

Because Wei had little credit history, his aunt became the co-signer on his apartment lease.

Common collocations
  • act as a co-signer
  • co-signer on a loan
  • co-signer for an apartment
  • find a co-signer
  • need a co-signer
  • serve as co-signer
Synonyms
  • guarantor

    a broader term covering any person who guarantees a debt or obligation, not only by signing

  • surety

    formal legal term; the surety may put up assets rather than just a signature

Antonyms

Grammar Patterns

co-signer + of + [agreement/document]

act as (a) co-signer

Usage Note

The co-signer is legally liable for the full amount borrowed, not just a share. Credit checks are normally run on the co-signer just as on the main applicant.

Common Mistakes

My father was a co-signer of the document.' (when paying a loan is meant).
My father was a co-signer on my student loan.
use 'on' or 'for' a specific financial agreement, not 'of' which fits sense 2 better.

2. any entity that formally endorses an official document alongside other parties,

2.nounC1
Definition

any entity that formally endorses an official document alongside other parties, signalling agreement or joint accountability by means of a signature

Example

Fourteen nations served as co-signers to the international climate agreement.

co-signer + to + [agreement]: formal joint participation

The trade treaty requires each co-signer to remove tariffs by the end of the year.

Common collocations
  • co-signer of a treaty
  • co-signer to an agreement
  • co-signer of a statement
  • serve as a co-signer
  • listed as a co-signer
Synonyms
  • cosignatory

    a more formal, legal variant with the same meaning

  • signatory

    broader — a signatory may be the only party signing, while a co-signer signs alongside others

Grammar Patterns

co-signer + of + [document/treaty/statement]

co-signer to + [agreement]

Usage Note

Unlike sense 1, this sense carries no financial guarantee. The co-signer merely signals joint endorsement of a statement, treaty, or resolution.

Common Mistakes

Canada was a co-signer on the new trade deal.
Canada was a co-signer of the new trade deal.
for treaties and official documents, 'of' is standard; 'on' is used for financial agreements (sense 1).

Word family

Synonym discussion

Sense: noun/1

In financial contexts, a co-signer signs alongside the main applicant and is equally liable for repayment, but typically does not receive the loan proceeds. A guarantor also promises to pay if the borrower defaults, though the term is wider and can cover non-financial guarantees. Surety is the most formal legal term and often involves pledging assets rather than merely signing. A co-borrower, unlike a co-signer, shares ownership of the loaned funds and has the right to use them. For example: 'Lars asked his mother to be a co-signer on his car loan, but she never drove the car' — whereas a co-borrower would have joint ownership of the vehicle.

co-signer ↗guarantor ↗surety ↗co-borrower

Common collocations

Nouns

Phrases

  • act as a co-signer
  • serve as a co-signer
  • find a co-signer
  • need a co-signer
  • listed as a co-signer

Prepositions

Etymology

LatinEnglish

Formed in the 19th century by adding the prefix 'co-' (meaning 'together, jointly', from Latin 'cum') to 'signer' (someone who signs, from Latin 'signare' meaning 'to mark, to sign'). The word originally referred to anyone who signed a document alongside others, and later developed the narrower financial-guarantee sense in the 20th century.

First known use

1903

1903, in the meaning defined above