a space absolutely devoid of matter: compare plenum (2)

a space from which as much air or other substance as possible has been removed, e.g. by an air pump

an air pressure below atmospheric pressure

(used before a noun) of, containing, producing, or using a partial vacuum

a vacuum chamber

a vacant space; a void

a state of isolation from outside influences

people who live in a vacuum … so that the world outside them is of no moment — Somerset Maugham