ple·num (plēnəm, plĕnəm)
n. pl. ple·nums or ple·na (plēnə, plĕnə)
1. An assembly or meeting with all members present.
2. A condition, space, or enclosure in which air or other gas is at a pressure greater than that of the outside atmosphere.
3. The condition of being full; fullness.
4. A space completely filled with matter.
5. A space lying above the ceiling in a building but below the next floor, especially one allowing movement of air between parts of the building.
[Latin plēnum (spatium), full (space), neuter of plēnus; see pelə-1 in the Appendix of Indo-European roots.]
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