Longevity
\lɔnˈʤɛvəti\
In general usage, longevity is often used to refer to long (or longer than expected) life. However, actuaries and demographers generally use ‘longevity’ as the converse of mortality.
Mortality relates to the likelihood of death whilst longevity relates to the likelihood of remaining alive. Longevity can also be used as a synonym for expectation of life or life expectancy.