kingdom Plantae king·domp·lan·tae uncommon noun 1. the taxonomic kingdom comprising all living or extinct plants SynonymsPlantaekingdom Plantaeplant kingdom Related words Broader terms kingdom Part of plantThallophytaTracheophytaplant orderBryophytaPteridophytaSpermatophytaPhanerogamae WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.