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1.
A filled space, or the concept of space as full of something.

1 a : a space or all space every part of which is full of matter b : an air-filled space in a structure; especially : one that receives air from a blower for distribution (as in a ventilation system)
2 : a general assembly of all members especially of a legislative body
3 : the quality or state of being full
Instead of thinking of the Universe as a vacuum dotted here and there with matter, consider it a plenum, a filled structure of space full of light, energy and particle/aniparticle pairs produced by the Zero Point Field fluctuation.
by Greg Banville November 25, 2003
 
2.
end piece
vents
by rosebud October 09, 2003