Old age
Old age consists of ages nearing or surpassing the average life span of human beings, and thus the end of the human life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

. Euphemism
A euphemism is the substitution of a mild, inoffensive, relatively uncontroversial phrase for another more frank expression that might offend or otherwise suggest something unpleasant to the audience...

s and terms for old people include seniors (American usage), senior citizens (British and American usage) and the elderly.

Old people have limited regenerative abilities and are more prone to disease, syndromes, and sickness than other adult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....