usnic acid

 
Pronunciation: /ˈʌznɪk/

noun

[mass noun] Biochemistry
  • a yellow crystalline compound which is present in many lichens and is used as an antibiotic.
    • A tricyclic phenol; chemical formula: C18H16O7

Origin:

mid 19th century: usnic from medieval Latin usnea (from Arabic ushnah 'moss') + -ic