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
No one knows this better than lichenologists, who study the symbiosis between fungi, algae and other microbes that form lichens.
—
Corrado Nai, Smithsonian Magazine, 25 June 2024
Race on the White River, learn about lichens, or go on a night hike with these events around the state.
—Karl Schneider, The Indianapolis Star, 13 June 2024
While working on a project about lichen symbiosis, Smith learned that many moth species blend in with lichen—such as the Merveille du Jour moth, which is now tattooed on their forearm.
—Allison Parshall, Scientific American, 14 May 2024
Visitors who entered the building’s rotunda could walk along the evolution of the earth before man’s appearance — baked vegetation covered with lichen, then a cross section of a California redwood tree that was nearly 6 feet in diameter, followed by animal including a mastodon, mammoth and a whale.
—Andrew Johnston, Chicago Tribune, 30 May 2024
See all Example Sentences for lichen 
Corrado Nai, Smithsonian Magazine, 25 June 2024
Race on the White River, learn about lichens, or go on a night hike with these events around the state.
—Karl Schneider, The Indianapolis Star, 13 June 2024
While working on a project about lichen symbiosis, Smith learned that many moth species blend in with lichen—such as the Merveille du Jour moth, which is now tattooed on their forearm.
—Allison Parshall, Scientific American, 14 May 2024
Visitors who entered the building’s rotunda could walk along the evolution of the earth before man’s appearance — baked vegetation covered with lichen, then a cross section of a California redwood tree that was nearly 6 feet in diameter, followed by animal including a mastodon, mammoth and a whale.
—Andrew Johnston, Chicago Tribune, 30 May 2024
See all Example Sentences for lichen
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'lichen.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
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Cite this Entry
“Lichen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lichen. Accessed 4 Jul. 2024.
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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