URUSHIOL

[uru.shi.ol] n [ISV, fr. Jp urushi lacquer + ISV [1]-ol] (1908): a mixture of pyrocatechol derivatives with saturated or unsaturated side chains of 15 or 17 carbon atoms that is an oily toxic irritant principle present in poison ivy and some related plants (genus Rhus) and in oriental lacquers derived from such plants