. . "The word \"longevity\" is sometimes used as a synonym for \"life expectancy\" in demography - however, the term \"longevity\" is sometimes meant to refer only to especially long lived members of a population, whereas \"life expectancy\" is always defined statistically as the average number of years remaining at a given age. For example, a population's life expectancy at birth is the same as the average age at death for all people born in the same year (in the case of cohorts)."@en .