an·​ti·​gen | \ ˈan-ti-jən How to pronounce antigen (audio) , -ˌjen \

Definition of antigen

: 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

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Other Words from antigen

antigenic \ ˌan-​ti-​ˈje-​nik How to pronounce antigenic (audio) \ adjective
antigenically \ ˌan-​ti-​ˈje-​ni-​k(ə-​)lē How to pronounce antigenically (audio) \ adverb
antigenicity \ ˌan-​ti-​jə-​ˈni-​sə-​tē How to pronounce antigenicity (audio) \ 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 So, rapid flu tests—aka, a rapid influenza diagnostic tests (RIDTs) are tests that can detect influenza viral antigens in respiratory tract specimens, according to the CDC. Leah Groth,, "Lizzo Just Shared Video of Her Rapid Flu Test on Instagram—But What Is That?," 17 Dec. 2019 Out of standard options, Birzer’s local oncologist had referred her for a novel treatment called chimeric antigen receptor T-cell therapy — or CAR-T. Birzer and Johnson knew the treatment was risky. Ilana Yurkiewicz, Smithsonian, "The Possibilities and Risks of Genetically Altering Immune Cells to Fight Cancer," 26 Oct. 2019 Eliciting immunity to antigens like NA may confer protection and reduce disease symptoms12. William Warren, Scientific American, "Sanofi Pasteur: fighting influenza by improving today and innovating for tomorrow," 18 Sep. 2019 My guess is that the pathogen remains in the joints and sheds the antigen. Linda Carroll, NBC News, "Possible clue to Lyme arthritis found in patients' inflamed joints," 18 June 2019 The process of division adds some random changes to the cell’s antigen receptor genes. Quanta Magazine, "Breakthrough DNA Editor Born of Bacteria," 6 Feb. 2015 Early recognition of avian antigen exposure and removal of the bedding or other irritant is critical to recovery for patients, Dempsey stressed. Sandee Lamotte, CNN, "The man whose duvet nearly killed him: How this medical mystery was solved," 18 Nov. 2019 Recently, urologists discovered that the antigens behave differently between people of mainly African ancestry and mainly European ancestry. Talis Shelbourne, Milwaukee Journal Sentinel, "Why are there racial disparities in cancer? Doctor gives clues in Milwaukee presentation," 12 Sep. 2019 The vaccines administered to babies and children each contain between one and 69 antigens, according to the CDC. Carolyn L. Todd, SELF, "What Parents Need to Know About the Immunization Schedule for Kids," 26 Aug. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'antigen.' 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 antigen

1908, in the meaning defined above

History and Etymology for antigen

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

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Time Traveler for antigen

Time Traveler

The first known use of antigen was in 1908

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Statistics for antigen

Last Updated

25 Jan 2020

Cite this Entry

“Antigen.” Dictionary, Merriam-Webster, Accessed 24 Feb. 2020.

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More Definitions for antigen


How to pronounce antigen (audio)

English Language Learners Definition of antigen

medical : a harmful substance that causes the body to produce antibodies


an·​ti·​gen | \ ˈant-i-jən How to pronounce antigen (audio) \

Medical Definition of antigen

: 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

Other Words from antigen

antigenic \ ˌant-​i-​ˈjen-​ik How to pronounce antigenic (audio) \ adjective
antigenically \ -​i-​k(ə-​)lē How to pronounce antigenically (audio) \ adverb

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More from Merriam-Webster on antigen

Spanish Central: Translation of antigen

Nglish: Translation of antigen for Spanish Speakers

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

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