plenum

noun

ple·​num ˈple-nəm  ˈplē- 

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

Examples of plenum in a Sentence

Recent Examples on the Web

Netanyahu’s combative speech was delivered to a relatively empty General Assembly plenum. —Oren Liebermann, CNN Money, 26 Sep. 2025

And it's beautifully sculpted, as the mid-engine is designed to always be visible from both inside and outside the car – the plenum being the centerpiece; a perfect balance of aesthetics and intake performance. —New Atlas, 28 Apr. 2025

Of course, that nothing much will change was largely self-evident by the fact that this NPC follows on the heels of last July’s third CCP plenum, where long-term goals were laid out: bolstering party-state capitalism, countering U.S. containment, boosting innovation, and entrenching loyalty to Xi. —Charlie Campbell, TIME, 5 Mar. 2025

Chemical Smell Chemical scents can be produced when the heat exchanger is not properly cycling heat from the combustion chamber into the plenum. —Timothy Dale, Better Homes & Gardens, 10 Jan. 2025

Word History

Etymology

borrowed from Latin plēnum, noun derivative from neuter of plēnus "full"; (sense 1a) after its use in the Lucullus book of Cicero's Academica to denote a space completely filled with matter (distinguished from ināne or vacuum "empty space"); (sense 2) apparently first from its use in Sweden in the eighteenth century to refer to a meeting of all members of the Riksdag — more at full entry 1

First Known Use

1678, in the meaning defined at sense 1a

Rhymes for plenum

• denim
• venom
• imipenem