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 time disruption can disrupt the body’s biology, so the immune system or metabolism might not work as well, according to reporting by PBS. — Hannah Poukish, Sacbee.com, 28 Oct. 2026

Back in 2023, Stevens revealed he was diagnosed with Guillain-Barré syndrome—a rare auto-immune disorder in which the body’s immune system attacks the nerves—and was working to relearn how to walk and use his hands. — Nina Corcoran, Pitchfork, 27 Oct. 2026

Patients with weakened immune systems or serious underlying conditions, as well as those with medical devices, such as catheters, face especially high risks. — ABC News, 27 Oct. 2026

The gut is lined with bacteria and other microorganisms that regulate the immune system. — Carrie Madormo, Verywell Health, 26 Oct. 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