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
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Integrative Medicine In Autoimmune Disorders Autoimmune diseases—including lupus, rheumatoid arthritis, Hashimoto’s thyroiditis, and multiple sclerosis—result from an overactive immune system attacking the body's own tissues. Jesse Pines, Forbes, 12 Mar. 2025 If exposed to measles, this population receives immunoglobulins — protein antibodies that help the immune system fight off harmful agents. Jia H. Jung, The Mercury News, 11 Mar. 2025 Chronic Health Conditions Various chronic health conditions, including diabetes, a weakened immune system, or metabolic syndrome, can all contribute to slow wound healing. Angelica Bottaro, Verywell Health, 11 Mar. 2025 Running myself ragged trying to catch up rarely ends well for my immune system and the shutdown method just makes matters worse. Patricia Shannon, Southern Living, 9 Mar. 2025 See All Example Sentences for immune system

Word History

First Known Use

circa 1919, in the meaning defined above

Time Traveler
The first known use of immune system was circa 1919

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Cite this Entry

“Immune system.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/immune%20system. Accessed 25 Mar. 2025.

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

More from Merriam-Webster on immune system

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