active immunity

noun

: usually long-lasting immunity that is acquired through production of antibodies within the organism in response to the presence of antigens compare passive immunity

Examples of active immunity 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.
Your active immunity is how your immune system responds to germs by producing its own antibodies. Leah Groth, Health, 17 Nov. 2023 But active immunity, achieved with mRNA, means the body can remember how to create the response on its own. Hope Reese, Discover Magazine, 23 Dec. 2021 In active immunity, antibodies are generated through exposure to a pathogen or a vaccine. Los Angeles Times, 3 Dec. 2020 But passive immunity doesn't last as long as active immunity, and loses effectiveness within a few weeks or months, per the CDC. Leah Groth, Health.com, 15 Apr. 2020

Word History

First Known Use

1893, in the meaning defined above

Time Traveler
The first known use of active immunity was in 1893

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Cite this Entry

“Active immunity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/active%20immunity. Accessed 8 Sep. 2025.

Kids Definition

active immunity

noun
: immunity produced by the individual when exposed to an antigen compare passive immunity

Medical Definition

active immunity

noun
: usually long-lasting immunity that is acquired through production of antibodies within the organism in response to the presence of antigens compare acquired immunity, innate immunity, passive immunity
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