mortality rate

noun

plural mortality rates
: the ratio between deaths and individuals in a specified population and during a particular time period : the incidence of deaths in a given population during a defined time period (such as one year) that is typically expressed per 1000 or 100,000 individuals : death rate
an annual mortality rate of 15 deaths per 1000 people

Note: A crude mortality rate does not distinguish between specific causes of death or groups of individuals and measures the incidence of all deaths in a population during a given time period. More specific mortality rates are based on narrower categories of individuals or causes of death.

an infant mortality rate of 9 deaths per 1000 live births
mortality rates of lung cancer patients
infectious disease mortality rates

Examples of mortality rate in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Studies show the vaccine has drastically reduced mortality rates from cervical cancer. Dr. Areta Bojko, ABC News, 24 June 2026 For breast cancer, mortality rates are 35% higher among Black women than among white women. Lily Alvino, NBC news, 24 June 2026 The United States has the highest maternal mortality rate of any wealthy nation, and the toll falls hardest on Black mothers and on rural families far from a delivery room. John Boozman, Time, 23 June 2026 Researchers noted a decline in the mortality rate for infants born at full term, at 39 to 40 weeks. Mike Stobbe, Los Angeles Times, 22 June 2026 See All Example Sentences for mortality rate

Word History

First Known Use

1855, in the meaning defined above

Time Traveler
The first known use of mortality rate was in 1855

Browse Nearby Words

Cite this Entry

“Mortality rate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mortality%20rate. Accessed 28 Jun. 2026.

Medical Definition

mortality rate

noun
: the ratio between deaths and individuals in a specified population and during a particular time period : the incidence of deaths in a given population during a defined time period (such as one year) that is typically expressed per 1000 or 100,000 individuals : death rate
an annual mortality rate of 15 deaths per 1000 people

Note: A crude mortality rate does not distinguish between specific causes of death or groups of individuals and measures the incidence of all deaths in a population during a given time period. More specific mortality rates are based on narrower categories of individuals or causes of death.

mortality rates of liver cancer patients
an infant mortality rate of 9 deaths per 1000 live births
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