The organic process of ageing is called senescence, Definitions of old age include official definitions, sub-group definitions, and four dimensions as follows. Most developed-world countries have accepted the chronological age of 65 years as a definition of 'elderly' or older person.

Old age comprises "the later part of life; the period of life after youth and middle age . 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.

12 year old dating 16 year old-3812 year old dating 16 year old-18

It is used in general usage instead of traditional terms such as old person, old-age pensioner, or elderly as a courtesy and to signify continuing relevance of and respect for this population group as "citizens" of society, of senior rank.

It has come into widespread use in recent decades in legislation, commerce, and common speech.

Therefore, rather than lumping together all people who have been defined as old, some gerontologists have recognized the diversity of old age by defining sub-groups.

One study distinguishes the young old (60 to 69), the middle old (70 to 79), and the very old (80 ).

The age which qualifies for senior citizen status varies widely.

In governmental contexts it is usually associated with an age at which pensions or medical benefits for the elderly become available.In commercial contexts, where it may serve as a marketing device to attract customers, the age is often significantly lower.and the CPP (Canada Pension Plan) as early as age 60.Some dictionaries describe widespread use of "senior citizen" for people over the age of 65.When defined in an official context, senior citizen is often used for legal or policy-related reasons in determining who is eligible for certain benefits available to the age group.), the elderly, and elders (in many cultures—including the cultures of aboriginal people).