greying
noun [ U ]
( US graying) uk/ˈɡreɪɪŋ/ usa situation in which the number of older people living in an area is increasing because people are living longer:
The greying of the British population is one of the major challenges to the economy of the coming decades.
the process of becoming old and living longer:
Increased longevity and the greying of the post-war baby-boomers mean that many more will have to save a lot more money for a comfortable retirement.
greying
adjective
uk/ˈɡreɪɪŋ/ usa greying society or country is one in which the number of older people is increasing because people are living longer:
Japan's greying population