Senior citizen

Old age refers to ages nearing or surpassing the life expectancy of human beings, and is thus the end of the human life cycle. In October 2016, a highly publicized paper claimed the maximum human lifespan is an average age of 115, with an absolute upper limit of 125 years, but the authors' methods and conclusions are controversial. Terms and euphemisms for old people include, old people (worldwide usage), seniors (American usage), senior citizens (British and American usage), older adults (in the social sciences), the elderly, and elders (in many cultures—including the cultures of aboriginal people).

Old people often have limited regenerative abilities and are more susceptible to disease, syndromes, and sickness than younger adults. The organic process of ageing is called senescence, the medical study of the aging process is called gerontology, and the study of diseases that afflict the elderly is called geriatrics. The elderly also face other social issues around retirement, loneliness, and ageism.

The chronological age denoted as "old age" varies culturally and historically. Thus, old age is a "social construct" rather than a definite "biological stage".

In 2011, the United Nations proposed a human rights convention that would specifically protect older persons.

Definitions of old age include official definitions, sub-group definitions, and four dimensions as follows.

Old age comprises "the later part of life; the period of life after youth and middle age . . . , usually with reference to deterioration". At what age old age begins cannot be universally defined because it differs according to the context. Most developed-world countries have accepted the chronological age of 65 years as a definition of 'elderly' or older person. The United Nations has agreed that 60+ years may be usually denoted as old age and this is the first attempt at an international definition of old age. However, for its study of old age in Africa, the World Health Organization (WHO) set 50 as the beginning of old age. At the same time, the WHO recognized that the developing world often defines old age, not by years, but by new roles, loss of previous roles, or inability to make active contributions to society.

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