Definition of mortality
1
: the quality or state of being mortal
- Her husband's death reminded her of her own mortality.
2
: the death of large numbers (as of people or animals)
- trying to reduce infant mortality
4
: the human race
- that natural extinction to which all mortality is subject
- —Thomas Paine
5 a
: the number of deaths in a given time or place
- The mortality among the infected mounted daily.
b
: the proportion of deaths to population
- a brain infection with a mortality rate of about 30 percent
- —Jane E. Brody
c
: the number lost or the rate of loss or failure
- the mortality rate of small businesses
