guarantor

/ˌɡɛrənˈtɔr/
noun
  1. A person or organization that promises to pay a debt or perform an obligation if the person who is supposed to do so fails.
    • The company served as a guarantor for the project's financing.
    • The bank required a guarantor before approving the student loan.
    • Her uncle acted as a guarantor for her apartment lease.
  2. A person or thing that ensures something will happen or be maintained.
    • The constitution is the guarantor of our basic rights.
    • Trust is the guarantor of a healthy relationship.
    • A strong legal system is the guarantor of a fair society.