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 research on this new therapy is focused on the immune system, a new way to slow the progression of the disease. — Stephanie Stahl, CBS News, 13 Aug. 2026

So, the notion that vaccines in any way weaken or overwhelm or perturb our immune system is just nonsensical. — Mary Kekatos, ABC News, 13 Aug. 2026

Over the last five years, German researcher Georg Schett has made a name for himself as a pioneer in autoimmune disease treatment, showing that CAR-T therapy could be used to reset patients’ immune systems. — Allison Deangelis, STAT, 12 Aug. 2026

This allows the immune system to detect things that would otherwise remain hidden, including pieces of viruses and abnormal proteins. — William A. Haseltine, Forbes.com, 12 Aug. 2026

Word History

First Known Use

1899, in the meaning defined above

Rhymes for immune system

• cryptosystem
• ecosystem
• intersystem
• multisystem
• photosystem
• subsystem

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