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

These children die early in life unless their impaired immune system is re-created with bone-marrow transplants. —Jerome Groopman, New Yorker, 6 Apr. 2026

Older children and adults with weakened immune systems also are vulnerable. —Don Sweeney april 6, Sacbee.com, 6 Apr. 2026

Adults older than 65, pregnant women, and people with weakened immune systems should avoid egg coffee because raw eggs pose a salmonella risk. —Emily Kay Votruba, EverydayHealth.com, 6 Apr. 2026

This is primarily because some adaptogens can interact with medications, influence hormone levels or stimulate the immune system in ways that may worsen underlying conditions or alter how some drugs are metabolized. —Daryl Austin, USA Today, 5 Apr. 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