From Latin plēnum, noun use of neuter of plēnus ‎(full). Influenced by Russian пле́нум ‎(plénum, plenary session), from the same Latin source.



plenum ‎(plural plenums or plena)

  1. (physics) A space that is completely filled with matter.
    • 1946, Bertrand Russell, A History of Western Philosophy:
      The idea was that a thing could only move into an empty place, and that, in a plenum, there are no empty places.
    • 2001, Edward Grant, God and Reason in the Middle Ages, p. 176:
      The key to understanding medieval interpretations of motion in hypothetically void space is to realize that medieval natural philosophers analyzed the same bodies in the void that they discussed in the plenum of their ordinary world.
  2. (figuratively) A state of fullness, a great quantity (of something).
    • 1974, Guy Davenport Tatlin!:
      He lay on the long stone slant down to the slapping waves, his denim shorts, sneakers, and socks under his head for a pillow, feeling the splendour of distance in all directions, the liquid silence, the plenum of aloneness.
  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. (computing) A type of network cabling which satisfies plenum-ratings issued by the National Electrical Code. These cables are safer in case of a fire, producing less smoke and fumes.


Related termsEdit







  1. In public; somewhere (sometime) where and when everyone's allowed: not restricted to a certain group or the like.
    Thomas Giertsen var på apoteket og kassapersonen annonserte at han hadde en soppinfeksjon høyt i plenum så alle hørte det.
    Thomas Giertsen was in the apothecary and the pharmacist announced loudly his fungal infection to those present in the shop.

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