n 1 : any of several plants included in the genus Rhus or sometimes in the genus Toxicodendron that produce an irritating oil like that of poison ivy: a : a bushy plant (R. diversiloba syn. T. diversilobum) of the Pacific coast b : a bushy plant (R. toxicodendron syn. T. pubescens) of the southeastern U.S. 2 : POISON IVY 1a 3 : a skin rash produced by poison oak .
Similar sounding terms: pac·ing
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