old age; senescence
Refers to the stage of life after middle age, often used in medical, psychological, or sociological contexts.
Even after entering old age, I want to take care of my health.
老年期 refers to old age, the life stage opposite to 幼少期's early childhood.
Compound of 老年 (rounen, 'old age') + 期 (ki, 'period, stage').