poison ash poi·so·nash uncommon noun 1. smooth American swamp shrub with pinnate leaves and greenish flowers followed by greenish white berries; yields an irritating oil Synonymspoison ashpoison dogwoodpoison sumacToxicodendron vernixRhus vernix Related words Broader terms poisonous plant Parts Toxicodendron WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
