mortality (mor-TA-lih-tee)
The state of being mortal (destined to die). Mortality also refers to the death rate, or the number of deaths in a certain group of people in a certain period of time. Mortality may be reported for people who have a certain disease, live in one area of the country, or who are of a certain gender, age, or ethnic group.
Source: The National Cancer Institute's Dictionary of Cancer Terms
(http://www.cancer.gov/dictionary)