mea·​sles | \ ˈmē-zəlz How to pronounce measles (audio) \

Definition of measles

1a : an acute contagious disease that is caused by a morbillivirus (species Measles morbillivirus) and is marked especially by an eruption of distinct red circular spots

called also rubeola

b : any of various eruptive diseases (such as German measles)
2 [Middle English mesel infested with tapeworms, literally, leprous, from Anglo-French, from Medieval Latin misellus leper, from Latin, wretch, from misellus, diminutive of miser miserable] : infestation with or disease caused by larval tapeworms in the muscles and tissues

Examples of measles in a Sentence

Recent Examples on the Web All states have the power to require vaccination among students attending school; many do for diseases like polio and measles. Robert Hart, Forbes, "Only Half Of Americans Say They Will Vaccinate Their Children Against Covid-19 As Soon As They're Eligible," 6 Apr. 2021 That would make the vaccine more akin to vaccines against measles than flu vaccines. Maggie Fox, CNN, "How long will coronavirus vaccines protect people?," 4 Apr. 2021 Experts say at least 92% of the population must be vaccinated against measles to prevent it from spreading. The Salt Lake Tribune, "What Utah childhood vaccination rates can, and can’t, reveal about demand for COVID-19 vaccine," 25 Mar. 2021 While some wild gorillas were vaccinated against measles in the 1980s, there are currently no plans to vaccinate them against the coronavirus. Fox News, "Zoos, scientists aim to protect animals from people spreading coronavirus," 19 Mar. 2021 If a high percentage of people statewide are vaccinated against measles, but that number is low in a specific community within that state, then people living in that place are vulnerable. Kathleen Hall Jamieson, Scientific American, "How to Debunk Misinformation about COVID, Vaccines and Masks," 18 Mar. 2021 Scientists estimate at least 90% of a population must be vaccinated against measles to create herd immunity. Zachary Orlins, ABC News, "The high price of low vaccination rates: How a single measles outbreak cost $3.4 million," 11 Mar. 2021 To reach herd immunity against measles, for example, which is very infectious, requires about 95% of a population to be vaccinated according to the World Health Organization. Kristen Jordan Shamus, Detroit Free Press, "COVID-19 vaccines, herd immunity and more: We answer your questions," 27 Feb. 2021 But in reality, it is used in the tuberculosis vaccine, or Bacille Calmette-Guerin, given in developing countries, as well as the oral polio, measles and live flu vaccine. Miriam Fauzia, USA TODAY, "Fact check: Trump's past flu vaccinations not linked to increased COVID-19 risk," 21 Oct. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'measles.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of measles

14th century, in the meaning defined at sense 1a

History and Etymology for measles

Middle English meseles, plural of mesel measles, spot characteristic of measles; akin to Middle Dutch masel spot characteristic of measles

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Time Traveler for measles

Time Traveler

The first known use of measles was in the 14th century

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Last Updated

15 Apr 2021

Cite this Entry

“Measles.” Dictionary, Merriam-Webster, Accessed 16 Apr. 2021.

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English Language Learners Definition of measles

: a disease that causes a fever and red spots on the skin


mea·​sles | \ ˈmē-zəlz How to pronounce measles (audio) \

Kids Definition of measles

1 : a contagious disease in which there are fever and red spots on the skin
2 : any of several diseases (as German measles ) resembling true measles


noun plural but singular or plural in construction
mea·​sles | \ ˈmē-zəlz How to pronounce measles (audio) \

Medical Definition of measles

1a : an acute contagious disease that is caused by a paramyxovirus of the genus Morbillivirus (species Measles morbillivirus), that commences with catarrhal symptoms, conjunctivitis, cough, and Koplik's spots on the oral mucous membrane, and that is marked by the appearance on the third or fourth day of an eruption of distinct red circular spots which coalesce in a crescentic form, are slightly raised, and after the fourth day of the eruption gradually decline

called also rubeola

b : any of various eruptive diseases (as German measles)
2 : infestation with or disease caused by larval tapeworms in the muscles and tissues specifically : infestation of cattle and swine with cysticerci of tapeworms that as adults parasitize humans — compare measle

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More from Merriam-Webster on measles

Nglish: Translation of measles for Spanish Speakers

Britannica English: Translation of measles for Arabic Speakers Encyclopedia article about measles

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