1. plural of plenum; spaces filled with matter, especially air at atmospheric pressure, or enclosed spaces in which air or fluid circulates
Usage: technical; often used in HVAC and engineering contexts
2. plural of plenum; full assemblies or sessions, especially of a legislative or deliberative body
Usage: formal; political or institutional context

Examples

• The HVAC system uses plenums to distribute air throughout the building.
• The ceiling plenums contain electrical wiring and ductwork.
• The parliament held several plenums to debate the new legislation.
• Air plenums must be properly sealed to maintain system efficiency.
• The conference included multiple plenums with all delegates present.