immune system

noun

: the bodily system that protects the body from foreign substances, cells, and tissues by producing the immune response and that includes especially the thymus, spleen, lymph nodes, special deposits of lymphoid tissue (as in the gastrointestinal tract and bone marrow), macrophages, lymphocytes including the B cells and T cells, and antibodies

Examples of immune system in a Sentence

Recent Examples on the Web

Tell us in the comments, and then read the related article about surging flu cases or this one about how to boost your immune system. Students 13 and older in the United States and Britain, and 16 and older elsewhere, are invited to comment. —The Learning Network, New York Times, 18 Feb. 2025

These may include the virus persisting in parts of the body, long-lasting disruption of the immune system, clotting in microscopic blood vessels, or changes to the bacteria and viruses that naturally inhabit our bodies. —Farah Aziz Annesha, The Mercury News, 16 Feb. 2025

But it’s been well-established that PFAS are linked to serious health issues including multiple types of cancer, suppression of the immune system, thyroid disease, decreased fertility, and liver and kidney damage. —Bethany Mavis, Outside Online, 16 Feb. 2025

This citrus fruit may help boost your immune system and lower your risk of some health conditions. —Melissa Nieves, Verywell Health, 12 Feb. 2025

Word History

First Known Use

circa 1919, in the meaning defined above

Kids Definition

immune system

noun

: the bodily system that protects the body from foreign substances, cells, and tissues by producing the immune response and that includes especially the thymus, spleen, lymph nodes, lymphocytes, and antibodies

Medical Definition

immune system

noun

: the bodily system that protects the body from foreign substances, cells, and tissues by producing the immune response and that includes especially the thymus, spleen, lymph nodes, special deposits of lymphoid tissue (as in the gastrointestinal tract and bone marrow), lymphocytes including the B cells and T cells, and antibodies