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

She has been diagnosed with retinitis pigmentosa, an eye disease that causes vision loss, and lupus, a disease where the immune system mistakenly attacks healthy tissues and organs instead of fighting germs, according to court records. — Chase Jordan july 30, Charlotte Observer, 30 July 2026

Additionally, doctors often recommend over-the-counter antihistamines such as Benadryl to counteract histamine released by the immune system. — Maggie O'Neill, Verywell Health, 29 July 2026

Many will require a strict diet because their owners would often have fed them the wrong food, weakening an animal's immune system and causing physical deterioration. — ABC News, 29 July 2026

Severe diarrhea and vomiting can also lead to dehydration, electrolyte imbalances and complications that are especially dangerous for children, older adults and people with weakened immune systems, experts warn. — Khloe Quill, FOXNews.com, 29 July 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