greys

1. An achromatic colour intermediate between black and white.
2. An animal or thing of grey colour, such as a horse, badger, or salmon.
3. An extraterrestrial humanoid with greyish skin, bulbous black eyes, and an enlarged head.

1. To become grey.

   My hair is beginning to grey.

2. To cause to become grey.
3. To turn progressively older, in the context of the population of a geographic region.

   the greying of Europe

4. To give a soft effect to (a photograph) by covering the negative while printing with a ground-glass plate.

noun

Grey trousers and/or jackets worn by prisoners on relatively formal occasions.