The character 青 (qīng) describes color: 青天 (qīngtiān) for the sky, 青山 (qīngshān) for the mountains, 青丝(qīngsī) for hair , 青眼 (qīngyǎn) for eyes… One color can be used to describe all of these different entities. What color is 青 anyway? When used with different nouns to form fixed words and phrases, qing could be green, blue, or close to black.
In most cases, qing refers to green, such as 青草 (qīngcǎo, green grass), 青山 (qīngshān, green mountains), 青菜 (qīngcài, green vegetables), and 青椒 (qīngjiāo, green pepper). The ancient dictionary 释名 The Shiming defines it as: 青，生也，象物生时色也 (qīng, shēng yě, xiàng wù shēng shí sè yě). Qing, is birth, like the color of things born. Thus, 青春 (qīngchūn), literally “green spring”, means youth.
But qing can also sometimes mean blue. The Confucian philosopher Xunzi once said: “青，取之于蓝，而青于蓝” (qīng, qǔ zhī yú lán, ér qīng yú lán), or “Qing comes from blue, yet excels blue”. Blue, in this context, refers to bluegrass, which was used to dye items the color of qing. The sentence “青出于蓝而胜于蓝” (qīng chū yú lán ér shèng yú lán) has become a fixed expression, used to describe how the student could excel the teacher.
Finally, qing may also refer to the color black. 青鬓 (qīng bìn) means black temple hair, which in ancient China was a term that could be used to refer to young people. 青衣 (qīngyī) refers to a main female role in Chinese opera, which comes from the fact that most of them wear black clothing.