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

Even small amounts of mercury can cause severe damage to the nervous, digestive and immune systems, as well as to the lungs, kidneys, skin and eyes. —Antonio María Delgado, Miami Herald, 24 Mar. 2026

Immune Dysregulation Research increasingly suggests that the immune system may play a role in ASD, both throughout the body and within the brain. —Wyles Daniel, USA Today, 23 Mar. 2026

There are medications that can train you immune system not to overreact to allergens. —Kenya Hunter, Chicago Tribune, 22 Mar. 2026

Based on the Japanese wellness practice of Shinrin-yoku, the activity has been known to reduce stress, improve mood, lower blood pressure and boost the immune system. —ABC News, 22 Mar. 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