Someone or something that is ageing is becoming older and less healthy or efficient.
old , elderly
young , new
John lives with his ageing mother.
约翰和他日渐衰老的母亲住在一起。
Ageing aircraft need more frequent safety inspections.
老化的飞机需要更加频繁的安全检查。
Ageing is the process of becoming old or becoming worn out.
The only signs of ageing are the flecks of grey that speckle his dark hair.
他变老的惟一迹象是散布在黑发中的几缕银丝。