Bible Dictionaries
Plenum

Webster's Dictionary

(1):

(n.) A condition, as in an occupied room, in which the pressure of the air is greater than that of the outside atmosphere; as, a plenum may exist in a hall ventilated by a fan blower.

(2):

(n.) That state in which every part of space is supposed to be full of matter; - opposed to vacuum.

Bibliography Information
Webster, Noah. Entry for 'Plenum'. Noah Webster's American Dictionary. https://www.studylight.org/​dictionaries/​eng/​web/​p/plenum.html. 1828.