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

Psoriatic arthritis is a chronic (long-term) autoimmune condition in which your immune system attacks healthy tissues, causing joint pain, swelling, and stiffness. — Health Editorial Team, HEALTH, 3 Nov. 2026

Petosemtamab targets the proteins EGFR and LGR5, and is designed to both disrupt signals that help cancer cells grow and to encourage the immune system to attack the tumor. — Elsa Ohlen, CNBC, 3 Nov. 2026

The innate immune system's main attack strategy is triggering inflammation. — New Atlas, 1 Nov. 2026

Neoantigens are proteins that arise from changes in cancer cells and can help the immune system distinguish tumors from healthy tissue. — Neetika Walter, Interesting Engineering, 31 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