Absence of matter. A space empty of matter. A space relatively empty of matter. A space in which the pressure is significantly lower than atmospheric pressure. A state of emptiness; a void. A state of being sealed off from external or environmental influences; isolation. A vacuum cleaner. Of, relating to, or used to create a vacuum. Containing air or other gas at a reduced pressure. Operating by means of suction or by maintaining a partial vacuum. To clean with or use a vacuum cleaner.