n.1. a. The hue of that portion of the visible spectrum lying between orange and green, evoked in the human observer by radiant energy with wavelengths of approximately 570 to 590 nanometers; any of a group of colors of a hue resembling that of ripe lemons and varying in lightness and saturation; one of the subtractive primaries; one of the psychological primary hues.
b. A pigment or dye having this hue.
c. Something that has this hue.
2. Chiefly Southern US The yolk of an egg.
3. Western US Gold. Used formerly by prospectors.
4. yellows Any of various plant diseases characterized by yellow or yellowish discoloration of the leaves and caused by phytoplasmas that are transmitted by insects or by certain viruses.