01 n. That state in which every part of space is supposed to be full of matter; -- opposed to vacuum.
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1.
That state in which every part of space is supposed to be full of matter; -- opposed to vacuum.
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2.
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.(Ventilation)