(y)u̇ˈrüshēˌȯl, -ēˌōl noun
( -s )
Etymology: International Scientific Vocabulary urushi + -ol
: a poisonous oily liquid phenolic compound C 15 H 27 C 6 H 3 (OH) 2 in the sap of Oriental lacquer trees ( Rhus verniciferi and R. succedanea ) and present also as one of the principal blistering substances in poison ivy, poison oak, and poison sumac that hardens and becomes colored by atmospheric oxidation and serves as the chief component of Japanese and Chinese lacquers; 3-pentadeca-trien-yl-pyrocatechol