Definition of plenum in US English:



  • 1An assembly of all the members of a group or committee.

    ‘the seventh plenum of the Communist Party central committee’
    • ‘The struggle is likely to come to a head at the next plenum of the Communist Party Central Committee due later this month.’
    • ‘Labour's support is needed to send the bill to committee and then to the full plenum for passage in three separate votes that would set the ball rolling toward an election as early as February.’
    • ‘During the committee's 12th plenum, which ended Tuesday, the body voted separately for individual candidates.’
    • ‘Islam views the world as a plenum, capable of neither diminishment nor amplification.’
    • ‘The growing number of resignations from the party was discussed at every level of the conference - in the plenum itself as well as during the breaks.’
    • ‘The week-long plenum that opened April 10 in Hanoi has signaled that preparations are well under way for next year's party congress (one is held every five years).’
    • ‘Since the second meeting also assembled a quorum, the two plenums yielded two mutually exclusive, but equally valid, results.’
    • ‘Molotov lost the post of foreign minister in 1949; and, from 1952, his career fell into eclipse when Stalin criticized him at a Central Committee plenum.’
    • ‘The plenum was of crucial symbolic importance for Mr Hu.’
    • ‘He said the next plenum of the central committee, scheduled after local party congresses from August this year to before March next year, will touch upon personnel matters for a new party leadership.’
    • ‘Then they hand out little circular mirrors to each member of the plenum.’
    • ‘The seventh and eight plenums, held in August and November 1999, began preparations for the Ninth National Party Congress scheduled for the first quarter of 2001.’
    • ‘A further plenum of the Central Committee met in Wuhan on 28 November.’
    • ‘The purpose of the directives will be to " catch up with the new situation " following the fourth plenum of the Communist Party central committee held from September 16 to 19.’
    • ‘In a break with party tradition, he started publishing the agenda of the party's plenums to make them available for public debate.’
    • ‘The Central Committee's plenum reiterated its determination to shore up the party's ability to govern the country.’
    • ‘So decided the socialist plenum over the weekend.’
    • ‘The decision-making Central Committee of the Communist Party of Vietnam started a plenum Monday in Hanoi to prepare documents for the party's congress scheduled for March next year, according to party sources.’
    • ‘That led to speculation that things might come to a head at the fourth plenum of the 16th Central Committee later this month.’
  • 2Physics
    A space completely filled with matter, or the whole of space so regarded.

    ‘so long as things move simultaneously into each other's places, motion is possible in a plenum’
    • ‘Imagine fracturing a material body such as a piece of wood, regarded as a plenum (full of matter).’
    • ‘The early universe was filled with radiation and a plenum of matter, originally hydrogen and helium, formed from elementary particles in the dense primeval fireball.’
    • ‘A quantum vacuum is more like a plenum than like empty space.’
    • ‘At a very deep subatomic level the differences of dualism melt into a plenum of potentiality or probability.’
    • ‘Even as late as the 17th century, Descartes imagined all space to be filled with little whirling vortices which he called the plenum.’
    1. 2.1 An enclosed chamber where a treated substance collects for distribution, as heated or conditioned air through a ventilation system.
      • ‘It acts like a big duct, serving as the return air plenum and natural ventilation shaft on fair weather days, and a thermal buffer during the morning heat gain.’
      • ‘Their size required only a shallow six-inch plenum over the suspended ceiling, thus reducing the needed floor to floor height.’
      • ‘Make sure the general contractor knows to clean the plenum space.’
      • ‘The floors are acoustically separated, and the space between them used as an air-distribution plenum.’
      • ‘In this system, a raised floor is divided into separate plenums to control the distribution, and these act as the ‘ductwork.’’
      • ‘Because they were installed with an enclosed plenum in a minimum depth of 18 inches, the panels also provide a .65 noise reduction coefficient.’
      • ‘1.1 What were the circumstances in which the canopy plenum / extract duct were destroyed?’
      • ‘Carbon dioxide levels in the plastic enclosure were manipulated by passing an air stream through a swamp cooler and into a plenum chamber underneath the enclosure that distributed it evenly over the floor of the enclosure.’
      • ‘‘The mechanical contractor who reads the spec sees that the plenum space should be cleaned before capping off with the floor,’ he says.’
      • ‘The plenum is a large sheet metal box that's attached to the top or bottom of the furnace.’
      • ‘The reality is that often the plenum space is left dirty after construction.’
      • ‘Use of a raised floor plenum with a radiant heating and cooling system will allow a displacement ventilation system to be used.’
      • ‘Clearly, all fires are dangerous, but those that originate in or spread to the plenum space above the ceiling or below a raised floor are of special concern.’
      • ‘The devices carry cables and wires through the plenum space and concrete slab to the floor above.’
      • ‘An aperture in the plenum directs air flow out of the plenum.’
      • ‘In these under-floor spaces are large ducts that push the conditioned air into the plenum and up under the seats.’
      • ‘This strategy allows the floor level to be raised, and can be the plenum for distribution of conditioned air.’
      • ‘An air supported conveyor, particularly adapted for conveying articles such as baggage or packages at a high rate of speed includes a plenum chamber and a belt support containing a plurality of orifices.’


Late 17th century: from Latin, literally ‘full space’, neuter of plenus ‘full’.