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

Blocking this receptor has already been shown in past studies to enhance the effectiveness of T cells, the immune system’s frontline fighters against infections and tumors. —Discover Magazine, 17 Apr. 2025

There still needs to be more research done on how saunas might relieve stress on specific symptoms in the body, like the immune system. —Mara Santilli, Flow Space, 16 Apr. 2025

Even a slight change in a strain of influenza can result in the immune system’s inability to recognize the virus. —Hanna D. Paton, The Conversation, 15 Apr. 2025

Like the immune system, Haidt says kids are antifragile — meant to learn from challenges. —Rachel Hale, USA Today, 15 Apr. 2025

Word History

First Known Use

circa 1919, 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