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

In both conditions, the immune system is involved. —Ruth Jessen Hickman, Health, 10 Feb. 2026

Some drinks contain vitamins, minerals, and antioxidants that help support your immune system. —Cristina Mutchler, Verywell Health, 10 Feb. 2026

The high amount of vitamin C in noni juice also plays a vital role in its effect in boosting the immune system. —Bestreviews, Mercury News, 10 Feb. 2026

After learning that Casper had been diagnosed with Guillain Barré Syndrome, a condition in which the body’s immune system attacks the nerves, Aidan Oldenburg, Ben Richardson and Luc Violette needed somebody with experience that could help them in the interim. —Dane Mizutani, Twin Cities, 10 Feb. 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