aging

"Aging" can either be an adjective (as in, "an aging person") or a gerund (as in, "The person was aging rapidly").

Aging is usually considered as an unlucky or unsuccessful phenomenon, when there is a delay in aging it's called as a successful aging (i think)

The book "Aging Identity: A Dialogue with Postmodernism" examines aging from a point of view that aging is not a decline, but a dynamic change. It looks at aging and the attitude towards the elderly in different cultures and the diversity of aging peoples. The book also looks at the challenges and opportunities that come with aging.

The same as you did