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. Yellow is one of the three primary colors. The other two are red and blue.

yellow - easily frightened