• WordNet 3.6
    • n lichen any thallophytic plant of the division Lichenes; occur as crusty patches or bushy growths on tree trunks or rocks or bare ground etc.
    • n lichen any of several eruptive skin diseases characterized by hard thick lesions grouped together and resembling lichens growing on rocks
    • ***
Webster's Revised Unabridged Dictionary
    • Lichen (Med) A name given to several varieties of skin disease, esp. to one characterized by the eruption of small, conical or flat, reddish pimples, which, if unchecked, tend to spread and produce great and even fatal exhaustion.
    • Lichen (Bot) One of a class of cellular, flowerless plants, (technically called Lichenes), having no distinction of leaf and stem, usually of scaly, expanded, frond-like forms, but sometimes erect or pendulous and variously branched. They derive their nourishment from the air, and generate by means of spores. The species are very widely distributed, and form irregular spots or patches, usually of a greenish or yellowish color, upon rocks, trees, and various bodies, to which they adhere with great tenacity. They are often improperly called rock moss or tree moss.
    • ***
Century Dictionary and Cyclopedia
    • n lichen In botany, a plant or vegetable growth of the group Lichenes, ordinarily recognizable by its dry aspect and gray, brown, greenish, or blackish color, and its appearance in crusts, scaly patches, or bush-like forms on trees, rails, rocks, etc. Lichens also grow on the ground, and some (the Collemei, or jelly-lichens) form, when wet, a pulpy or gelatinous mass. Lichens are distributed through all lands, enduring great extremes of temperature and the severest drought, living often where nothing else can. They corrode the hardest rocks, thus contributing to the formation of soil. The lichens most useful for food are the Iceland moss (see Cetraria), the reindeer-moss (see Cladonia and reindeer-moss), the manna-lichen (see Lecanora), and the rock-tripe (see Umbilicaria). Various lichens furnish the blue or purple dyestuffs known as archil, cudbear, and litmus. The Iceland moss has a demulcentworth; but for the most part the medicinal virtues of lichens are imaginary.
    • n lichen In pathology, an eruption of papules, of a red or pale color, which do not reach a vesicular or pustular stage. They may be in clusters or scattered, or disseminated over the surface of the skin; and may be attended with itching, as in lichen ruber, or may be quite free from it, as in lichen scrofulosorum.
    • lichen To lichenize.
    • ***
Chambers's Twentieth Century Dictionary
    • n Lichen lī′ken one of an order of cellular flowerless plants: an eruption on the skin
    • ***


Webster's Revised Unabridged Dictionary
L., fr. Gr. leichh`n
Chambers's Twentieth Century Dictionary
L.,—Gr. leichēnleichein, to lick.


In literature:

Lucien soon informed them that it was not a "moss," but a "lichen," and of that celebrated species which will sustain human life.
"Popular Adventure Tales" by Mayne Reid
It seemed as if they would continue there rooted, like some ancient lichen growth in a forest.
"Young Hilda at the Wars" by Arthur Gleason
They bear resemblance to lichen planus papules.
"Essentials of Diseases of the Skin" by Henry Weightman Stelwagon
Going on, I walked for some distance beneath a semi-arch of the wind-bowed lichenous thorns that grow upon the cliff-edge.
"A Poor Man's House" by Stephen Sydney Reynolds
The number of fungi is also large; and the tree often supports lichens, algae, and other forms of life.
"The Apple-Tree" by L. H. Bailey
First come the lichens which need no soil; on the remains of these the mosses grow.
"Ontario Teachers' Manuals: Nature Study" by Ontario Ministry of Education
The ground was covered with soft grass and round elastic cushions of gray lichen.
"Hopes and Fears scenes from the life of a spinster" by Charlotte M. Yonge
Its plumage is like a mirror which reflects the snow, the moss, or the lichens in turn.
"The Log of the Sun" by William Beebe
The rocks were quite bare, without so much as the slightest sign of a lichen.
"Celebrated Travels and Travellers" by Jules Verne
He's all for going out and looking for lichen, but Pat says he's got to set up camp, then get instructions from Earth.
"The Dope on Mars" by John Michael Sharkey

In poetry:

Parasite lichen
Lies grey on the years;
Lily buries herself
When winter appears.
"Lichen" by Mary Eliza Fullerton
Bright rose burns away,
Leaving lichen alone—
Fellow of frost,
Suckling of stone.
"Lichen" by Mary Eliza Fullerton
"Where elder and the sumach creep
Above your garden's paling,
Whereon at noon the lizards sleep
Like lichens on the railing.
"One Day And Another: A Lyrical Eclogue – Part I" by Madison Julius Cawein
We shall wander through the meaning
Of a day and see no light,
For our lichened arms are leaning
On the ends of endless night.
"The Three Witches" by Ernest Christopher Dowson
Why should I speak of what has been?
Or what dark part I played in all?
Why ruin sits in porch and hall
Where pride and gladness once were seen;
And why beneath this lichened wall
The grave of Margaret is green.
"The Brothers" by Madison Julius Cawein
I see them gray among their ancient acres,
Severe of front, their gables lichen-sprinkled,—
Like gentle-hearted, solitary Quakers,
Grave and religious, with kind faces wrinkled,—
Serene among their memory-hallowed acres.
"Old Homes" by Madison Julius Cawein

In news:

Lichen Loop at Heil Ranch.
A hiker stands between two lichen -covered rocks on Lichen Trail following a spring snowstorm.
The cause of lichen planus is not known.
In areas where you have lichens : Do you dislike the look, or are you afraid it's damaging the walkways and deck.
While some people aren't keen on the look of lichen decorating their paths and buildings, others like the rustic look.
The likelihood of lichen hurting or damaging surfaces that it clings to is very small.
"There was an old study in England in which they sent schoolchildren to collect lichens , and found that you get fewer lichens the closer you get to an industrial area," Hill said.
None is more mysterious or delightful to behold than the lowly lichen.
Dangling 1,200 feet above Franconia Notch, Niels Nielsen sprays bleach on the Old Man's face to kill lichen and moss that grow in cracks.
Availability of these lichens may determine the nesting locations of parula warblers in East Tennessee.
Lizard, fish, lichen also named for Obama.
Lichens and turtles star in two public lectures at UW.
BEAUMONT — We routinely get calls concerning lichens, ball moss, and mistletoe found growing in our trees.
Ball moss, lichens and mistletoe are commonly found growing on shade trees in Texas.
Before the Mariner flybys in the 1960s, scientists thought Mars had water and life, even if it was just some sort of plantlike lichen.

In science:

Brieskorn, Die Fundamentalgruppe des Raumes der regul¨aren Orbits einer end lichen komplexen Spiegelugsgruppe, Invent.
Artin groups of spherical type up to isomorphism
Remak, ˜Uber die Darstel lung der end lichen Gruppen als Untergruppen direkter Produkte, J. reine Angew.
Second maximal subgroups of the finite alternating and symmetric groups
Theorie der end lichen und unend lichen Graphen.
Factor complexity of infinite words associated with non-simple Parry numbers
Thoma, Die unzerlegbaren, positive-definiten Klassenfunktionen der abz¨ahlbar unend lichen, symmetrischen Gruppe, Math.
Random Walks on Strict Partitions
Die unipotenten Charaktere fur die GAP-Charaktertafeln der end lichen Gruppen vom Lie-Typ, Diplomarbeit.
Simple linear groups $PSL_4(q)$ are determined by the set of their character degrees