plenum

1. A space that is completely filled with matter.
2. A state of fullness, a great quantity (of something). (figuratively)
3. A legislative meeting (especially of the Communist Party) in which all members are present.
4. An enclosed space having greater than atmospheric pressure.
5. The space above a false ceiling used for cables, ducts etc.
6. A type of network cabling which satisfies a given plenum rating for the purpose of fire safety.

الجمع plenums