infectious disease

noun

: a disease (such as influenza, malaria, meningitis, rabies, or tetanus) caused by the entrance into the body of pathogenic agents or microorganisms (such as bacteria, viruses, protozoans, or fungi) which grow and multiply there compare communicable disease, contagious disease

Examples of infectious disease 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.
California in 2026 has already seen its highest number of annual measles cases in seven years, health officials said, amid an ongoing resurgence of a notoriously infectious disease once considered effectively eliminated in the United States. Los Angeles Times, 16 Apr. 2026 Meanwhile, measles cases in the US are at their highest level in three decades, and the nation risks losing its status as a country that has eliminated ongoing transmission of the highly infectious disease within its borders. Sarah Owermohle, CNN Money, 16 Apr. 2026 Lopman, an infectious disease epidemiologist now at Emory University, was living in London when his son got sick. Lauren Dunn, NBC news, 15 Apr. 2026 If the cells are too different from those of the donor, transplant complications such as GVHD could be more of a concern, says Björn-Erik Ole Jensen, head of the infectious disease department at the University Hospital of Dusseldorf, who was not involved in this study. Emma Gometz, Scientific American, 13 Apr. 2026 See All Example Sentences for infectious disease

Word History

First Known Use

1600, in the meaning defined above

Time Traveler
The first known use of infectious disease was in 1600

Browse Nearby Words

Cite this Entry

“Infectious disease.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infectious%20disease. Accessed 21 Apr. 2026.

Kids Definition

infectious disease

noun
: a disease caused by the presence, growth, and increase in numbers of germs in the body

Medical Definition

infectious disease

noun
: a disease (as influenza, malaria, meningitis, rabies, or tetanus) caused by the entrance into the body of pathogenic agents or microorganisms (as bacteria, viruses, protozoans, or fungi) which grow and multiply there compare communicable disease, contagious disease
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