• Plenum chamber, a chamber intended to contain air, gas, or liquid at positive pressure
• Plenism, or Horror vacui ("nature abhors a vacuum")
• Plenum, a meeting of a deliberative assembly in which all members are present; contrast with quorum
• Plenum space, enclosed spaces (in buildings) used for heating, ventilating, and/or air-conditioning airflow
• Plenum cable, electrical cabling permitted under building codes in plenum spaces
• Plenum filtration, a type of aquarium filtration using a deep sand bed with a gap below it
• Plenum Publishing Corporation, a publisher of scientific books and journals that was acquired by Springer Science+Business Media

See also

• Plenary, the related adjective