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

After ruling out all other possibilities, Dhingra finally diagnosed Williams with IC‑MPGN, a kidney disease related to the immune system. — Kerry Breen, CBS News, 27 June 2026

To understand what was happening in the skin, Kaplan’s team took a deeper look at mast cells, among the immune system’s first responders. — ABC News, 27 June 2026

Reishi mushrooms may ease allergy symptoms by helping balance the immune system and reducing histamine release, though much of the supporting evidence still comes from laboratory research rather than large human trials. — Samantha Agate, Miami Herald, 26 June 2026

Reishi is not a same-day fix the way a pharmacy antihistamine can be, and its benefits build gradually as the compounds work on the immune system over time. — Samantha Agate, Kansas City Star, 26 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