What is "law of mortality"

Mortality \Mor*tal"i*ty\, n. [L. mortalitas: cf. F. mortalit['e].]

1. The condition or quality of being mortal; subjection to death or to the necessity of dying.

   When I saw her die, I then did think on your mortality.
   --Carew.

2. Human life; the life of a mortal being.

   From this instant There 's nothing serious in mortality.
   --Shak.

3. Those who are, or that which is, mortal; the human race; humanity; human nature.

   Take these tears, mortality's relief.
   --Pope.

4. Death; destruction.
   --Shak.

5. The whole sum or number of deaths in a given time or a given community; also, the proportion of deaths to population, or to a specific number of the population; death rate; as, a time of great, or low, mortality; the mortality among the settlers was alarming.

   Bill of mortality. See under Bill.

   Law of mortality, a mathematical relation between the numbers living at different ages, so that from a given large number of persons alive at one age, it can be computed what number are likely to survive a given number of years.

   Table of mortality, a table exhibiting the average relative number of persons who survive, or who have died, at the end of each year of life, out of a given number supposed to have been born at the same time.