From Longman Dictionary of Contemporary Englishlichenli‧chen /ˈlaɪkən, ˈlɪtʃən/ noun [uncountable] HBa grey, green, or yellow plant that spreads over the surface of stones and trees → moss
Examples from the Corpus
lichen• Maybe I was on some damp lichen.• Their route became a steep scramble between white boulders speckled with green and grey lichen.• Leicestershire for example, lost 89 percent of the vulnerable species in its lichen flora and 47 percent overall.• Subtleties in the texture of the grit, patches brushed clean of lichen, told him where to place his feet.• The triumphant plant, a combination of lichen and cactus, certainly would look weird to the eyes of man.• Only a nearby ash tree, which had better buffered bark, retained the lichen.• These majestic stones, flecked with orange and white lichen, are the last of thousands that once littered the prehistoric landscape.• The walls are black and slimy with lichen and pigeon shit.Origin lichen (1600-1700) Latin Greek leichen 