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

That protein then trains the immune system to learn to attack cancer cells. — Kiki Intarasuwan, CBS News, 20 Aug. 2026

Immunotherapy is a medication that helps the patient’s own immune system fight the cancer. — Maggie Donahue, HEALTH, 20 Aug. 2026

It’s made with green tea to provide energy while suppressing your appetite, and goji berry to help your immune system. — Bestreviews, Chicago Tribune, 20 Aug. 2026

While most healthy individuals recover within a week, some infections may result in a serious complication known as hemolytic uremic syndrome (HUS), particularly in young children, older adults, and individuals with weakened immune systems. — Michele Laufik, Martha Stewart, 20 Aug. 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