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

Two had suppressed immune systems before contracting the disease. — Susanne Rust follow, Los Angeles Times, 23 July 2026

Tick saliva also contains a number of other immune-affecting compounds that can modify the immune system, says Pritt. — Alice Park, Time, 23 July 2026

Salmonella is an organism that can cause serious and sometimes fatal infections in young children, elderly people and those with weakened immune systems. — Mary Lyle, Arkansas Online, 23 July 2026

Speaking of mistaken, Sjögren’s disease is kind of a case of mistaken identity— where your immune system somehow thinks your normal body tissue is something to be attacked. — Bruce Y. Lee, Forbes.com, 21 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