undecylenic acid
noun
un·dec·y·le·nic acid ˌən-ˌde-sə-ˈle-nik- 
-ˈlē-
-ˈlē- : a fatty acid C11H20O2 found in perspiration, obtained commercially from castor oil, and used especially in the treatment of fungal infections (such as ringworm) of the skin
Word History
Etymology
undecylene (C11H22)
First Known Use
1879, in the meaning defined above
Medical Definition
undecylenic acid
noun
un·dec·y·le·nic acid ˌən-ˌdes-ə-ˌlen-ik- -ˌlēn-
-ˌlēn- : an acid C11H20O2 found in perspiration, obtained commercially from castor oil, and used in the treatment of fungus infections (as ringworm) of the skin