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vismīļākā no visām krāsiņām
Green is the color of growing grass, leaves and emeralds.[2][3] [4] On the spectrum of visible light, it is located between blue and yellow. It is evoked by light with a predominant wavelength of roughly 495–570 nm.

The modern English word green comes from the Middle English and Anglo-Saxon word grene, from the same Germanic root as the words "grass" and "grow".[5] By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into energy.

In surveys made in Europe and the United States, green is the color most commonly associated with nature, youth, spring, hope and envy. In western culture It is the color of permission and safety. [6] It is also often associated with the culture of Gaelic Ireland, and with the environmental movement.[7] In China green is the symbol of fertility.[7] It is the most important color in Islam. It was the color of the banner of Muhammad, and is found in the flags of all Islamic countries, and represents the lush vegetation of Paradise.[8]

Etymology and linguistic definitions
The word green comes from the Middle English and Old English word grene, which, like the German word grün, has the same root as the words grass and grow.[10] It is from a Common Germanic *gronja-, which is also reflected in Old Norse grænn, Old High German gruoni (but unattested in East Germanic), ultimately from a PIE root *ghre- "to grow", and root-cognate with grass and to grow.[11] The first recorded use of the word as a color term in Old English dates to ca. AD 700.[12]

Latin with viridis (and hence the Romance languages, and English vert, verdure etc.) also has a genuine term for "green". Likewise the Slavic languages with zelenъ. Ancient Greek also had a term for yellowish, pale green – χλωρός, chloros (cf. the color of chlorine), cognate with χλοερός "verdant" and χλόη "the green of new growth".

Thus, the languages mentioned above (Germanic, Romance, Slavic, Greek) have old terms for "green" which are derived from words for fresh, sprouting vegetation. However, comparative linguistics makes clear that these terms were coined independently, over the past few millennia, and there is no identifiable single Proto-Indo-European or word for "green". For example, the Slavic zelenъ is cognate with Sanskrit hari "yellow, ochre, golden".[13] The Turkic languages also have jašɨl "green" or "yellowish green", compared to a Mongolian word for "meadow".[14]

Languages where green and blue are one color - šitas man vairāk nepatī. Riebjas!

n some languages, including old Chinese, Thai, old Japanese, and Vietnamese, the same word can mean either blue or green.[15] The Chinese character 青 (pronounced qīng in Mandarin, ao in Japanese, and thanh in Sino-Vietnamese) has a meaning that covers both blue and green; blue and green are traditionally considered shades of "青". In more contemporary terms, they are 藍 (lán, in Mandarin) and 綠 (lǜ, in Mandarin) respectively. Japanese also has two terms that refer specifically to the color green, 緑 (midori, which is derived from the classical Japanese descriptive verb midoru "to be in leaf, to flourish" in reference to trees) and グリーン (guriin, which is derived from the English word "green"). However, in Japan, although the traffic lights have the same colors that other countries have, the green light is described using the same word as for blue, "aoi", because green is considered a shade of aoi; similarly, green variants of certain fruits and vegetables such as green apples, green shiso (as opposed to red apples and red shiso) will be described with the word "aoi". Vietnamese uses a single word for both blue and green, xanh, with variants such as xanh da trời (azure, lit. "sky blue"), lam (blue), and lục (green; also xanh lá cây, lit. "leaf green").

"Green" in modern European languages corresponds to about 520–570 nm, but many historical and non-European languages make other choices, e.g. using a term for the range of ca. 450–530 nm ("blue/green") and another for ca. 530–590 nm ("green/yellow").[citation needed] In the comparative study of color terms in the world's languages, green is only found as a separate category in languages with the fully developed range of six colors (white, black, red, green, yellow, and blue), or more rarely in systems with five colors (white, red, yellow, green, and black/blue).[16] (See distinction of green from blue)[17] These languages have introduced supplementary vocabulary to denote "green", but these terms are recognizable as recent adoptions that are not in origin color terms (much like the English adjective orange being in origin not a color term but the name of a fruit). Thus, the Thai word เขียว besides meaning "green" also means "rank" and "smelly" and holds other unpleasant associations.[18]

The Celtic languages had a term for "blue/green/grey", Proto-Celtic *glasto-, which gave rise to Old Irish glas "green, grey" and to Welsh glas "blue". This word is cognate with the Ancient Greek γλαυκός "bluish green", contrasting with χλωρός "yellowish green" discussed above.

In modern Japanese, the term for green is 緑, while the old term for "blue/green", blue (青 Ao?) now means "blue". But in certain contexts, green is still conventionally referred to as 青, as in blue traffic light (青信号 ao shingō?) and blue leaves (青葉 aoba?), reflecting the absence of blue-green distinction in old Japanese (more accurately, the traditional Japanese color terminology grouped some shades of green with blue, and others with yellow tones).

The Persian language is traditionally lacking a black/blue/green distinction. The Persian word سبز sabz can mean "green", "black", or "dark". Thus, Persian erotic poetry, dark-skinned women are addressed as sabz-eh, as in phrases like سبز گندم گون sabz-eh-gandom-gun (literally "dark wheat colored") or سبز مليح sabz-eh-malih ("a dark beauty").[19] Similarly, in Sudanese Arabic, dark-skinned people are described as أخضر akhḍar, the term which in Standard Arabic stands unambiguously for "green".[20]

In science
In optics, the perception of green is evoked by light having a spectrum dominated by energy with a wavelength of roughly 495-570 nm. The sensitivity of the dark-adapted human eye is greatest at about 507 nm, a blue-green color, while the light-adapted eye is most sensitive about 555 nm, a slightly yellowish green; these are the peak locations of the rod and cone (scotopic and photopic, respectively) luminosity functions.[21]
The perception of greenness (in opposition to redness forming one of the opponent mechanisms in human color vision) is evoked by light which triggers the medium-wavelength M cone cells in the eye more than the long-wavelength L cones. Light which triggers this greenness response more than the yellowness or blueness of the other color opponent mechanism is called green. A green light source typically has a spectral power distribution dominated by energy with a wavelength of roughly 487–570 nm.[22]

Human eyes have color receptors known as cone cells, of which there are three types. In some cases, one is missing or faulty, which can cause color blindness, including the common inability to distinguish red and yellow from green, known as deuteranopia or red–green color blindness.[23] Green is restful to the eye. Studies show that a green environment can reduce fatigue.[24]

In the subtractive color system, used in painting and color printing, green is created by a combination of yellow and blue, or yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. On the HSV color wheel, also known as the RGB color wheel, the complement of green is magenta; that is, a color corresponding to an equal mixture of red and blue light (one of the purples). On a traditional color wheel, based on subtractive color, the complementary color to green is considered to be red.[25]
In additive color devices such as computer displays and televisions, one of the primary light sources is typically a narrow-spectrum yellowish-green of dominant wavelength ~550 nm; this "green" primary is combined with an orangish-red "red" primary and a purplish-blue "blue" primary to produce any color in between – the RGB color model. A unique green (green appearing neither yellowish nor bluish) is produced on such a device by mixing light from the green primary with some light from the blue primary.

Pigments and dyes
Aside from chlorophyll, the green pigment of growing grass and leaves, green pigments are rather rare in nature.

Emeralds, are colored green by trace amounts of chromium and sometimes vanadium.[26]
Malachite, like many greens, is colored by the presence of copper, in this case by basic copper(II) carbonate.[27]
Green earth is a natural pigment used since the time of the Roman Empire. It is composed of clay colored by iron oxide, magnesium, aluminum silicate, or potassium. Large deposits were found in the South of France near Nice, and in Italy around Verona, on Cyprus, and in Bohemia. The clay was crushed, washed to remove impurities, then powdered. It was sometimes called Green of Verona.[28]
Verdigris is made by placing a plate or blade of copper, brass or bronze, slightly warmed, into a vat of fermenting wine, leaving it there for several weeks, and then scraping off and drying the green powder that forms on the metal. The process of making verdigris was described in ancient times by Pliny. It was used by the Romans in the murals of Pompeii, and in Celtic medieval manuscripts as early as the 5th century AD. It produced a blue-green which no other pigment could imitate, but it had drawbacks; it was unstable, it could not resist dampness, it did not mix well with other colors, it could ruin other colors with which it came into contact., and it was toxic. Leonardo da Vinci, in his treatise on painting, warned artists not to use it. It was widely used in miniature paintings in Europe and Persia in the 16th and 17th centuries. Its use largely ended in the late 19th century, when it was replaced by the safer and more stable chrome green.[29]
Cobalt green, sometimes known as Rinman's green or Zinc Green, is a translucent green pigment made by heating a mixture of cobalt (II) oxide and zinc oxide. Sven Rinman, a Swedish chemist, discovered this compound in 1780.[30]
Green chrome oxide was a new synthetic green created by a chemist named Pannetier in Paris in about 1835.
Emerald green was a synthetic deep green made in the 19th century by hydrating chrome oxide. It was also known as Guignet Green.[31]
Cobalt green, sometimes known as Rinman's green or Zinc Green, is a translucent green pigment made by heating a mixture of cobalt (II) oxide and zinc oxide. Sven Rinman, a Swedish chemist, discovered this compound in 1780.[30]
Green chrome oxide was a new synthetic green created by a chemist named Pannetier in Paris in about 1835.
Emerald green was a synthetic deep green made in the 19th century by hydrating chrome oxide. It was also known as Guignet Green.[31]
Viridian, also called chrome green, is a pigment made with chromium oxide dihydrate, was patented in 1859. It became popular with painters, since, unlike other synthetic greens, it was stable and not toxic. Vincent van Gogh used it, along with Prussian blue, to create a dark blue sky with a greenish tint in his painting Cafe terrace at night.[31]
Green has also often been made by mixing blue and yellow pigments. In antiquity, the Egyptians often mixed Egyptian blue and Naples yellow, while in the 19th century a color named English green was made by mixing Prussian blue and chrome yellow. Mixtures of oxidized cobalt and zinc were also used to create green paints as early as the 18th century.[32]
Amazonite. For many years, the source of amazonite's color was a mystery. Widely thought to have been due to copper because copper compounds often have blue and green colors, the blue-green color is likely to be derived from small quantities of lead and water in the feldspar.[33]
Phthalocyanine is an intense green synthetic dye which was accidentally created by Swiss chemists in 1927.
Food coloring and fireworks
There is no natural source for green food colorings which has been approved by the US Food and Drug Administration. Chlorophyll, the E numbers E140 and E141, is the most common green chemical found in nature, and only allowed in certain medicines and cosmetic materials.[34] Quinoline Yellow (E104) is a commonly used coloring in the United Kingdom but is banned in Australia, Japan, Norway and the United States.[35] Green S (E142) is prohibited in many countries, for it is known to cause hyperactivity, asthma, urticaria, and insomnia.[36]

To create green sparks, fireworks use barium salts, such as barium chlorate, barium nitrate crystals, or barium chloride, also used for green fireplace logs.[37] Copper salts typically burn blue, but cupric chloride (also known as "campfire blue") can also produce green flames.[37] Green pyrotechnic flares can use a mix ratio 75:25 of boron and potassium nitrate.[37] Smoke can be turned green by a mixture: solvent yellow 33, solvent green 3, lactose, magnesium carbonate plus sodium carbonate added to potassium chlorate.[37]
Why leaves and grass are green
Leaves and growing fresh grass are green because they contain a natural pigment known as chlorophyll. Chlorophyll takes the energy of sunlight and uses it to convert carbon dioxide and water into chemical energy, in the form of glucose, or natural sugar, which allows the plant to grow. This process is called photosynthesis. Chlorophyll absorbs the long wavelengths (red) and short wavelengths (blue) of the light, but the green light is reflected, making the grass and leaves appear green.[23] Chlorophyll does not absorb green light because it first arose in organisms living in oceans where purple halobacteria were already exploiting photosynthesis. Their purple color arose because they extracted energy in the green portion of the spectrum using bacteriorhodopsin. The new organisms that then later came to dominate the extraction of light were selected to exploit those portions of the spectrum not used by the halobacteria.[38]
Biology

Animals typically use the color green as camouflage, blending in with the chlorophyll green of the surrounding environment.[23] Green animals include, especially, amphibians, reptiles, and some fish, birds and insects. Most fish, reptiles, amphibians, and birds appear green because of a reflection of blue light coming through an over-layer of yellow pigment. Perception of color can also be affected by the surrounding environment. For example, broadleaf forests typically have a yellow-green light about them as the trees filter the light. Turacoverdin is one chemical which can cause a green hue in birds, especially.[23] Invertebrates such as insects or mollusks often display green colors because of porphyrin pigments, sometimes caused by diet. This can causes their feces to look green as well. Other chemicals which generally contribute to greenness among organisms are flavins (lychochromes) and hemanovadin.[23] Humans have imitated this by wearing green clothing as a camouflage in military and other fields. Substances that may impart a greenish hue to one's skin include biliverdin, the green pigment in bile, and ceruloplasmin, a protein that carries copper ions in chelation.