1 [ uncountable ] ( also morˈtality ˌrate / $ .’… / ) the number of deaths during a particular period of time among a particular type or group of people :
Mortality from heart disease varies widely across the world.
infant/child/maternal/adult mortality
an appallingly high infant mortality rate (= number of babies who die )
2 [ uncountable ] the condition of being human and having to die OPP immortality :
My mother’s death forced me to face the fact of my own mortality .
3 [ countable ] technical a death :
mortalities from cancer