n. The act or state of decreasing; the becoming gradually less; lessening; waste.n. The quantity lost by gradual diminution or waste; specifically, in mathematics, the small part by which a variable quantity becomes less and less.n. In heraldry, the condition of waning: said of the moon. It is represented by turning the horns of the crescent toward the sinister side. Also called detriment.n. In crystallography, a successive diminution of the layers of molecules applied to the faces of the primitive form, by which the secondary forms are hypothetically produced.