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

Deactivating the alpha-gal gene was a critical first step to make sure the human immune system wouldn’t immediately reject the foreign organs. —Matthew Perrone, Fortune, 13 June 2026

Normally this sugar coat triggers the immune system to kill the cancer cells. —Charles J. Dimitroff, The Conversation, 12 June 2026

The company focuses on blood stem cells, arguing that deterioration in the body's blood and immune systems may be one of the central drivers of aging. —Dasha Shunina, Forbes.com, 11 June 2026

Not long after, her father was diagnosed with multiple myeloma, an incurable blood cancer with recurring tumors that eat away at bone marrow, damaging bones and the immune system. —Vanessa Etienne, PEOPLE, 11 June 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