: 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

Time Traveler
The first known use of undecylenic acid was in 1879

Browse Nearby Words

Cite this Entry

“Undecylenic acid.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/undecylenic%20acid. Accessed 8 Jul. 2026.

Medical Definition

: an acid C11H20O2 found in perspiration, obtained commercially from castor oil, and used in the treatment of fungus infections (as ringworm) of the skin

More from Merriam-Webster on undecylenic acid

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

More from Merriam-Webster