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]