Legal Definition of Security: (a) Property that has been pledged by a lien or mortgage, thus guaranteeing that the creditor will be paid if the debtor defaults. Security makes the promise to pay more than a personal obligation. (b) A stock or bond that signifies that the borrower (the Corporation) owes a specified amount of money to the stock or bond holder. (c) Measures to protect people against attack, robbery, danger, etcetera | Discover the legal definition of security and its implications for business owners. Learn how security can include property collateral, stocks, and bonds, as well as measures to protect against threats. Protect your business, assets, and ensure the safety of your employees and customers with the right security measures. Invest in security for long-term success