n. The act of pressing down, or the state of being pressed down. Specificallyn. In astronomy: n. In gunnery, the lowering of the muzzle of a gun, corresponding to the raising of the breech.n. In surgery, a kind of couching.n. In music, the lowering or flatting of a tone: denoted in printed music by a ♭, or, after a ♯, by a ♯.n. A hollow; a sinking or falling in of a surface; a forcing inward: as, roughness consisting in little protuberances and depressions; the depression of the skull.n. Figuratively, the act of lowering or abasing: as, the depression of pride.n. A sinking of the spirits; dejection; a state of sadness; want of courage or animation: as, depression of the mind.n. A low state of strength; physical exhaustion.n. A state of dullness or inactivity: as, depression of trade; commercial depression.n. Humiliation, fall.n. Melancholy, despondency.n. The difference between the low barometric pressure and the normal pressure for that locality; the departure of the pressure.