a meeting of a legislative body at which all members are present
The plenum will vote on all tax increases.
source: WordNet 3.0
an enclosed space in which the air pressure is higher than outside
source: WordNet 3.0
That state in which every part of space is supposed to be full of matter; -- opposed to vacuum.
source: Webster 1913
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.
