noun
old age; senescence
Refers to the stage of life after middle age, often used in medical, psychological, or sociological contexts.
老年期に入っても、健康に気をつけたい。
Even after entering old age, I want to take care of my health.
高齢期 is a similar term meaning 'advanced age period', often used in gerontology and social welfare contexts.
Compound of 老年 (rounen, 'old age') + 期 (ki, 'period, stage').