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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That includes consistent interaction with music, which can have a positive impact on immune system responses, according to the American Journal of Public Health. Chase Jordan, Charlotte Observer, 8 Apr. 2025 For example, measles can make autoimmune diseases, in which the immune system mistakenly attacks one’s own body, go into remission. Sarah Zhang, The Atlantic, 7 Apr. 2025 For instance, scientists know that changes in estrogen could alter certain parts of the immune system and boost inflammation. Claire Bugos, Verywell Health, 7 Apr. 2025 As to why the shot may have this positive effect on brain health, Hopkins speculates that immune system stimulation may be a factor, adding that more research is needed to explore this potential benefit. Tom Gavin, EverydayHealth.com, 7 Apr. 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 19 Apr. 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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