Undecylenic :: Undecylenic (a.) Pertaining to, or designating, an acid C11H20O2, homologous with acrylic acid, and obtained as a white crystalline substance by the distillation of castor oil..
Undecylic :: Undecylic (a.) Related to, derived from, or containing, undecyl; specifically, designating that member of the fatty acids which corresponds to undecane, and is obtained as a white crystalline substance, C11H22O2..