* Formal: The bank required a guarantor to co-sign the loan.
* Informal: My parents agreed to be guarantors on my apartment lease.
* Legal: The contract stipulated that the guarantor would be responsible for any unpaid debts.
* Business: The company sought a guarantor for its new project to secure funding.
* Figurative: The weather was the guarantor of a successful outdoor festival.
Remember, "guarantor" refers to someone who promises to fulfill an obligation or debt if the original party fails to do so.