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

The bacteria grew so fast that the fungal immune system noticed them—and handily locked them away for disposal. —Molly Herring, WIRED, 26 Jan. 2025

This is a drug treatment used to boost a person's immune system response to cancer. —Steffini Stalos, Health, 25 Jan. 2025

After a few applications, the immune system begins to produce antibodies against immune complexes already bound to the viral protein. —Ashley MacKin Solomon, The Mercury News, 24 Jan. 2025

The immune system responds to these accumulations, sending macrophage white blood cells to engulf the cholesterol, which then turn into foam cells that aggregate in the skin, forming the yellowish plaques characteristic of xanthelasma. —Gordon G. Chang, Newsweek, 24 Jan. 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