noun Feelings of severe despondency and dejection. (self-doubt creeps in and that swiftly turns to depression) A long and severe recession in an economy or market. (the depression in the housing market) The action of lowering something or pressing something down. (depression of the plunger delivers two units of insulin) A region of lower atmospheric pressure, especially a cyclonic weather system. (hurricanes start off as loose regions of bad weather known as tropical depressions) The angular distance of an object below the horizon or a horizontal plane.