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 immune system is directly connected to the gut, so consuming the right nutrients can positively affect both. — Sadie Chafe, FOXNews.com, 13 Oct. 2026

Multiple sclerosis is a disease that affects the central nervous system and is considered an autoimmune disease, in which the immune system attacks its own healthy cells. — Alexandra Skores, CNN Money, 12 Oct. 2026

Mice without flagellin receptors were less affected—indicating a direct link between flagellin and an immune system response. — Jackie Flynn Mogensen, Scientific American, 9 Oct. 2026

In the livers of urban fish, 425 genes in juveniles and 585 in adults showed activity largely linked to inflammation and immune system responses that was not seen in damselfish living in clean, untouched reef areas. — New Atlas, 9 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