antigen

noun

an·​ti·​gen ˈan-ti-jən How to pronounce antigen (audio)
-ˌjen
: any substance (such as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (such as a protein) and that is capable of binding with a product (such as an antibody or T cell) of the immune response
antigenic adjective
antigenically adverb
antigenicity noun

Did you know?

An antibody is a protein produced by your immune system to fight outside invaders. Since the enemy substance actually triggers the production of antibodies, such substances are called antigens—anti- being short for antibody, and -gen meaning "producer". (In a similar way, an allergen produces an allergy, and a pathogen produces a pathology or disease.) Antigens are often rodlike structures that stick out from the surface of an invading organism—usually a bacterium or a virus—and allow it to attach itself to cells in the invaded body. But unfortunately for them, in doing so they let the immune system know they're present, and the body is flooded with an army of Pac-Man-like antibodies.

Examples of antigen in a Sentence

Recent Examples on the Web At-home antigen tests, though slightly less definitive, are painless, easy to complete and provide answers almost instantly. Robert Pearl, Forbes, 30 Sep. 2024 There are four ways to test for H. pylori: a urea breath test, a stool antigen test, an upper endoscopy, and a blood test. Elizabeth Yuko, Health, 26 Sep. 2024 The rapid antigen tests take about 30 minutes to give results. Deidre McPhillips, CNN, 26 Sep. 2024 In this case, the agency recommends having two to three negative antigen tests to rule out a COVID infection.4 Reporting your test results—positive or negative—can also be helpful in tracking the virus's spread throughout the U.S. Amber Brenza, Health, 24 Sep. 2024 See all Example Sentences for antigen 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'antigen.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

German, from French antigène, from anticorps antibody + -gène -gen

First Known Use

1908, in the meaning defined above

Time Traveler
The first known use of antigen was in 1908

Dictionary Entries Near antigen

Cite this Entry

“Antigen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/antigen. Accessed 15 Oct. 2024.

Kids Definition

antigen

noun
an·​ti·​gen ˈant-i-jən How to pronounce antigen (audio)
-ˌjen
: a substance (as a protein) that causes the body to form antibodies against it when it is introduced into the body either alone or as part of a microscopic plant or animal
antigenic adjective

Medical Definition

antigen

noun
an·​ti·​gen ˈant-i-jən How to pronounce antigen (audio)
: any substance (as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (as a protein) and that is capable of binding with a product (as an antibody or T cell) of the immune response
antigenic adjective
antigenically adverb

More from Merriam-Webster on antigen

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