Source : Webster's Revised Unabridged Dictionary (1913)

Terpenylic \Ter`pe*nyl"ic\, a. [Terpene + -yl + -ic.] (Chem.)
   Of, pertaining to, or designating, an acid, {C8H12O4} (called
   also terpentic acid), homologous with terebic acid, and
   obtained as a white crystalline substance by the oxidation of
   oil of turpentine with chromic acid.