Etymology and linguistic definitions
The word green
has the same Germanic root as the words for grass
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. 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.
The first recorded use of the word as a color term in Old English dates to ca. AD 700.
Latin with viridis also has a genuine and widely used term for "green". Related to virere "to grow" and ver "spring", it gave rise to words in several Romance languages, French vert, Italian verde (and English vert, verdure etc.). 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 "chloe, 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".
The Turkic languages also have jašɨl "green" or "yellowish green", compared to a Mongolian word for "meadow".
Languages where green and blue are one color
In some languages, including old Chinese, Thai, old Japanese, and Vietnamese, the same word can mean either blue or green. 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 as 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").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). (See distinction of green from blue) 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 kheīyw, besides meaning "green", also means "rank" and "smelly" and holds other unpleasant associations.
In the comparative study of
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"). Similarly, in Sudanese Arabic, dark-skinned people are described as أخضر akhḍar, the term which in Standard Arabic stands unambiguously for "green".