greying
adjective (US usually graying) uk/ˈɡreɪ.ɪŋ/ us/ˈɡreɪ.ɪŋ/
(HAIR)
变灰（白）色的（头发）;头发变灰（白）色的（某人）
used to describe a person whose hair is becoming grey or white, or the hair itself
He is short, with a greying beard. 他个头矮小，留着灰色的络腮胡。
(OLDER)
老年人数增加的，老龄化的
containing an increasing number of older people
Japan's greying population will drive up medical and pension payments. 日本人口老化将推高医疗和退休金开支。