Definitions for urushiolʊˈru ʃiˌɔl, -ˌɒl
Random House Webster's College Dictionary
u•ru•shi•olʊˈru ʃiˌɔl, -ˌɒl(n.)
a catechol derivative that is the irritant in poison ivy and its allies.
Origin of urushiol:
1910–15; < Japn urushi lacquer
An oil found in plants of the family Anacardiaceae, causing an allergic skin rash on contact; consists of a variable mixture of several organic compounds.
Origin: From うるし