Origin of plenum
- Latin plēnum (spatium) full (space) neuter of plēnus pelə-1 in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition
- From Latin plÄ“num, noun use of neuter of plÄ“nus (“full"). Influenced by Russian Ð¿Ð»ÐµÐ½ÑƒÐ¼ (plÃ©num, “plenary session"), from the same Latin source.