The class of securities that occupies the highest priority in a claim for principal, interest or dividends.

Notes, bonds, debentures, or preferred stocks whose claim on earnings and assets ranks ahead of common stock. Should a company liquidate, the claims of a senior security holders ranks above those of junior security holders because the company's creditors receive recompensation before the owners.

Securities that have a preferential claim over common stock on a company's earnings and in the case of liquidation. Generally, preferred stock and bonds are considered senior securities.