Illustration of lichen
- lichen 1
1
: any of numerous complex plantlike organisms made up of an alga or a cyanobacterium and a fungus growing in symbiotic association on a solid surface (such as on a rock or the bark of trees)
Note: The main body of the lichen, known as the thallus, is formed by fungal filaments which surround the photosynthetic algal or cyanobacterial cells. The lichen is usually described as having a leaflike (foliose), crusty (crustose), or branching shrub-like (fruticose) form. Lichens often play an important part in the weathering of rocks and include some that are sources of natural dyes.
2
: any of several skin diseases characterized by the eruptions of flat papules
Examples of lichen in a Sentence
Recent Examples on the Web
Much as hermit crabs borrow shells, fancy case caterpillars craft elaborate homes with sand, bits of plant material and lichen.
—
Elizabeth Weise, USA Today, 25 Apr. 2025
The wood is considered an iconic place, known not only for its collection of rare species of mosses and lichens only found within two small, wooded areas, but it is also embedded in the history, folklore and mythology of the area.
—Simon Perry, People.com, 31 Mar. 2025
Armed with precise instructions, children collected 8,000 samples of mosses and lichens from local parks, forests and other spots.
—Paulina Rowińska, Smithsonian Magazine, 12 Mar. 2025
Some 20 films from 17 countries, all of them focusing on and/or dedicated to the beauty of lichens, micro fungi and mushrooms, will be screened over two-plus hours.
—David L. Coddon, San Diego Union-Tribune, 3 Apr. 2025
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Elizabeth Weise, USA Today, 25 Apr. 2025
The wood is considered an iconic place, known not only for its collection of rare species of mosses and lichens only found within two small, wooded areas, but it is also embedded in the history, folklore and mythology of the area.
—Simon Perry, People.com, 31 Mar. 2025
Armed with precise instructions, children collected 8,000 samples of mosses and lichens from local parks, forests and other spots.
—Paulina Rowińska, Smithsonian Magazine, 12 Mar. 2025
Some 20 films from 17 countries, all of them focusing on and/or dedicated to the beauty of lichens, micro fungi and mushrooms, will be screened over two-plus hours.
—David L. Coddon, San Diego Union-Tribune, 3 Apr. 2025
See All Example Sentences for lichen
Cite this Entry
“Lichen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lichen. Accessed 15 May. 2025.
Copy CitationKids Definition
lichen
noun
li·chen
ˈlī-kən 
: any of numerous plantlike living things made up of an alga and a fungus growing together on a solid surface (as a rock or a tree)
Medical Definition
lichen
noun
li·chen
ˈlī-kən
1
: any of several skin diseases characterized by the eruption of flat papules
especially
: lichen planus
2
: any of numerous complex plantlike organisms made up of an alga and a fungus growing in symbiotic association on a solid surface (as a rock)
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