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 behavioral immune system, as scientists now call it, is a frontline defense, a set of psychological and physiological responses that detect and distance us from infectious threats before our biological immune system even has to get involved. —Scott Travers, Forbes.com, 16 May 2026

Probiotics also support the gut barrier and immune system. —Merve Ceylan, Health, 15 May 2026

Your brain processes information, and your immune system gets stronger. —Julie Scott, Verywell Health, 15 May 2026

Two weeks after implantation, the surrounding tissue showed little evidence of inflammation or immune system activity. —Aamir Khollam, Interesting Engineering, 15 May 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