Definition of Mortality

Mortality: A fatal outcome or, in one word, death. The word "mortality" is derived from "mortal" which came from the Latin "mors" (death). The opposite of mortality is, of course, immortality. Mortality is also quite distinct from morbidity (illness).

A condition such as tuberculosis can cause morbidity and mortality (disease and death). The Morbidity and Mortality Weekly Report (MMWR) is an important weekly publication by the US Centers for Disease Control and Prevention (the CDC).

A mortality rate is a death rate. There are a number of different types of mortality rates as, for example, the following:

• The fetal mortality rate: The ratio of fetal deaths to the sum of the births (the live births + the fetal deaths) in that year.
• The infant mortality rate: The number of children dying under a year of age divided by the number of live births that year.
• The maternal mortality rate: The number of maternal deaths related to childbearing divided by the number of live births (or by the number of live births + fetal deaths) in that year.