antigen
noun
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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
Melissa Cristina Márquez, Forbes.com, 11 July 2025
For men, a prostate specific antigen test is done and for women a pap smear.
—Nicole Villalpando, Austin American Statesman, 2 July 2025
Every routine childhood vaccine antigen appears in at least one such study.
—Jake Scott, The Conversation, 26 June 2025
Kids today are exposed to fewer antigens — immune-revving components — than their grandparents despite getting more doses, because of improved vaccine technology, said Dr. Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia.
—Lauran Neergaard, Chicago Tribune, 25 June 2025
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Cite this Entry
“Antigen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/antigen. Accessed 19 Jul. 2025.
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antigen
noun
Medical Definition
antigen
noun
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