Greys meaning : An achromatic colour intermediate between black and white. An animal or thing of grey colour, such as a horse, badger, or salmon. An extraterrestrial humanoid with greyish skin, bulbous black eyes, and an enlarged head. To become grey. To cause to become grey. To turn progressively older, in the context of the population of a geographic region. To give a soft effect to (a photograph) by covering the negative while printing with a ground-glass plate. Grey trousers and/or jackets worn by prisoners on relatively formal occasions.