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

Eating yogurt every day can benefit your immune system, too. —Kirsten Nunez, Martha Stewart, 2 May 2026

The resulting glut of insulin can inflame tissues all across the body, and over time, this can weaken the immune system and contribute to all manner of chronic diseases, including cancer and heart disease. —Ross Andersen, The Atlantic, 2 May 2026

Most people recover from treatment, but older adults, infants and people with weakened immune systems are more likely to develop severe illnesses from salmonellosis. —Greta Cross, USA Today, 1 May 2026

Doctors worried that his immune system was attacking his blood vessels, causing the necrotic lesions. —Beth Mole, ArsTechnica, 1 May 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