vacuum

n. (pl. -s or -cua) 1 space entirely devoid of matter. 2 space or vessel from which all or some of the air has been pumped out. 3 absence of the normal or previous content, activities, etc. 4 (pl. -s) colloq. Vacuum cleaner. v. Colloq. Clean with a vacuum cleaner. [latin vacuus empty]

n. A space entirely devoid of matter (called also, by way of distinction, absolute vacuum); hence, in a more general sense, a space, as the interior of a closed vessel, which has been exhausted to a high or the highest degree by an air pump or other artificial means; as, water boils at a reduced temperature in a vacuum.