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
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After another few minutes, King pointed out century-old tree trunks covered with lichen, a native witch-hazel bush blooming, its yellow flower a lone mark of color in a still-brown grove.
—
Robert Sullivan, Curbed, 9 June 2025
In any case, there are sure to be at least a few flecks of moss or lichen, gray or gray-green, on that side.
—Ted Updike, Outdoor Life, 22 May 2025
Intended to feel like a lush tree canopy, the dining room is a mix of forest green velvet banquettes, wooden high-top counters and low, stone tables with veining that looks like a web of lichen.
—Jen Murphy, Outside Online, 10 May 2025
Whether lichens can survive on Mars really depends on the species.
—Elizabeth Rayne, ArsTechnica, 19 Apr. 2025
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Robert Sullivan, Curbed, 9 June 2025
In any case, there are sure to be at least a few flecks of moss or lichen, gray or gray-green, on that side.
—Ted Updike, Outdoor Life, 22 May 2025
Intended to feel like a lush tree canopy, the dining room is a mix of forest green velvet banquettes, wooden high-top counters and low, stone tables with veining that looks like a web of lichen.
—Jen Murphy, Outside Online, 10 May 2025
Whether lichens can survive on Mars really depends on the species.
—Elizabeth Rayne, ArsTechnica, 19 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 19 Jun. 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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