Of a color between black and white

• Dull, dreary, or gloomy
• Indistinct, ambiguous, or morally uncertain
• Having gray hair
• Old or elderly
• Relating to older people as a group

To become gray

• To cause to become gray
• To age collectively, as a population
• To soften a photograph's contrast during printing

The achromatic color between black and white

• An animal or thing of gray color
• A gray whale, Eschrichtius robustus