(ˈəʊkˌmɒs) n (Plants) a type of lichen, or the essence produced from it, that is commonly found growing on oak trees and from which can be produced an essence that is used in the manufacture of perfumes
oak•moss
(ˈoʊkˌmɔs, -ˌmɒs)
n. a lichen, Evernia pranastri, growing on oak and other trees, yielding a resin used in the manufacture of perfumes. [1920–25]