Senior citizen is a common euphemism for an elderly person in both UK and US English, and it implies or means that the person is retired. This in turn usually implies or in fact means that the person is over the retirement age, which varies according to country. Synonyms include pensioner in UK English and retiree and senior in US English. Some dictionaries describe widespread usage of “senior citizen” for people over the age of 65. “Senior citizen” is replacing the term old-age pensioner traditionally used in UK English.
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.
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.
The term was apparently coined in 1938 during a political campaign. It has come into widespread use in recent decades in legislation, commerce, and common speech. Especially in less formal contexts, it is often abbreviated as “senior(s)”, which is also used as an adjective.
In commerce, some businesses offer customers of a certain age a “senior discount“. The age at which these discounts are available vary between 55, 60 or 65, and other criteria may also apply. Sometimes a special “senior discount card” or other proof of age needs to be obtained and produced to show entitlement.