—v.i. to diminish or lessen in extent, quantity, strength, power, etc.: During the ten-day march across the desert their supply of water decreased rapidly.
—v.t. to make less; cause to diminish: to decrease one's work load.
—n. 1. the act or process of decreasing; condition of being decreased; gradual reduction: a decrease in sales; a decrease in intensity. 2. the amount by which a thing is lessened: The decrease in sales was almost 20 percent.