The definition of a lichen is a plant found on rocks or trees made of both a specific fungus and a specific algae that help one another.(noun)
An example of a lichen is the colored patch growing on a tree branch.
See lichen in Webster's New World College Dictionary
Origin: L < Gr leichēn, prob. < leichein, to lick
See lichen in American Heritage Dictionary 4
Origin: Latin līchēn, a kind of plant
Origin: , from Greek leikhēn
Origin: , from leikhein, to lick; see leigh- in Indo-European roots.
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