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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Lymphoma is a type of cancer that starts in the lymphatic system, which is part of the body's immune system. Gagandeep Brar, Verywell Health, 28 Feb. 2025 But as mice get older, their fat tissue makes less proteins that help the body's immune system fight infection and inflammation (CX3CL1), which leads to lower levels of BDNF, a protein in the brain that helps nerve cells survive and grow. Dan Perry, Newsweek, 28 Feb. 2025 Due to microgravity, radiation and physiological stress, immune systems have to work harder in space to overcome infections. Sara Hashemi, Smithsonian Magazine, 28 Feb. 2025 These include exposure to microgravity and radiation that affect their immune responses; a human body with a healthy immune system needs to work harder in space to overcome the same infection that'd be relatively easier to fight off on Earth, according to NASA research. Sharmila Kuthunur, Space.com, 28 Feb. 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 10 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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