A cost that remains unchanged even with variations in output. An airline with 20 airplanes has the fixed costs of depreciation and interest (if the planes are partially financed with debt), regardless of the number of times the planes fly or the number of seats filled on each flight. Firms with high fixed costs tend to engage in price wars and cutthroat competition because extra revenues incur little extra expense. These firms tend to experience wide swings in profits. Compare variable cost.