Definition of lichen
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) ◆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 shrublike (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
lichenedplay \ˈlī-kənd, British also ˈli-chənd\ adjective
lichenousplay \ˈlī-kə-nəs, British also ˈli-chə-\ adjective
Recent Examples of lichen from the Web
Near the river, a large Garry Oak tree is swathed in fringes of lime-green lichen.
Not all tardigrades dwell in water; some species live in moss and lichens on trees.
Their nests are the size of half a walnut, and are made of plant down, lichen and moss, all weaved together with spider web.
Tree tannins, lichen and fungi, as well as flowers, leaves, stems and even roots were also transformed into dyes.
These trees are also an integral part of the forest ecosystem: moss and lichen grow on them, mushrooms sprout from the damp bark at their base.
Back in 2008, the space shuttle Atlantis carried an experiment to the International Space Station called EXPOSE-E—a module full of biological samples including organic molecules, microoraganisms, as well as lichens and fungi.
Here is the lichen turned crouton; here, the squid turned tartlet.
Speaking of plants, North American hummingbird nests are snug little cups typically woven together out of various types of plant matter, lichen, and spider silk.
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lichen.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
Origin and Etymology of lichen
Latin, from Greek leichēn, lichēn, from leichein to lick
First Known Use: circa 1657See Words from the same year
LICHEN Defined for English Language Learners
Definition of lichen for English Language Learners
: a type of small plant that grows on rocks and walls
LICHEN Defined for Kids
Definition of lichen for Students
: a plantlike organism made up of an alga and a fungus growing together
Medical Definition of lichen
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)
Seen and Heard
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