Yellow is the color evoked by light that stimulates both the L and M (long and medium wavelength) cone cells of the retina about equally, with no significant stimulation of the S (short-wavelength) cone cells. Light with a wavelength of 570–580 nm is yellow, as is light with a suitable mixture of somewhat longer and shorter wavelengths. Yellow’s traditional RYB complementary color is purple, violet, or indigo, while its colorimetrically defined complementary color in both RGB and CMYK color spaces is blue.
The word yellow comes from the Old English geolu, or geolwe which derived from the Proto-Germanic word gelwaz.Beowulf, in a description of a shield made of wood from a yew tree. The oldest known use of this word in English is in the Old English poem..
In the English language, yellow has traditionally been associated with jaundice and cowardice. Yellow is associated with the word „caution” and is the second light on stop lights; in American slang, a coward can be said to be „yellowbellied” or „yellow”. The color is associated with aging as well, for both people and objects (e.g. „yellowed” paper). Ethnographically, the term „yellow” has been used as a slang term for both Oriental persons („yellow peril„) and, in the early 20th century, light-skinned African-Americans (High yellow).
„Yellow” („giallo„), in Italy, refers to crime stories, both fictional and real. This association began in about 1930, when the first series of crime novels published in Italy had yellow covers. The term „yellow movie” (黃色電影) can refer to films of pornographic nature in Chinese culture, and is analogous to the English „blue movie„. Lastly, it is associated with sensational journalistic practices, or yellow journalism, and resistance to militant trade unions.