Was heißt vacuum? Was heißt vacuum? 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.