weight (wt) /wāt/ [AS, gewiht] , the force exerted on a body by gravitational attraction. As a body moves away from the earth, the weight of the body decreases, but the mass remains constant. In empty space a body has mass but no weight. Weight is sometimes measured in units of force such as newtons or poundals, but it is usually expressed in pounds or kilograms, as is mass. See also mass.