1an assembly of all the members of a group or committee:the seventh plenum of the Communist Party central committee
[influenced by Russian plenum 'plenary session']
2 Physics 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
Origin:
late 17th century: from Latin, literally 'full space', neuter of plenus 'full'
