A security agreement is a contract between a borrower and a lender that outlines the terms and conditions for securing a loan. Other words that can be used instead of security agreement include collateral agreement, pledge agreement, guarantee agreement, and mortgage agreement. A collateral agreement is a promise to secure a loan with an asset, such as a property or equipment. A pledge agreement is a commitment to secure a loan using a specific asset as collateral. A guarantee agreement is a contract where a third party agrees to cover any losses the lender may incur if the borrower defaults. Finally, a mortgage agreement is a contract that pledges real property as collateral for a loan.