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

She was put on antibiotics and received IVIG (Intravenous Immunoglobulin) to help her immune system. —Meredith Wilshere, PEOPLE, 20 Dec. 2025

Because these reactions are driven by the immune system—not infection—antibiotics are rarely necessary. —Taryn White, Travel + Leisure, 20 Dec. 2025

Our sauce includes onions for the heart and immune system, carrots that provide beta carotene for eye health and vitamin C, bell pepper for the immune system and celery with antioxidants that protect cells and reduce inflammation. —Bethany Thayer, Freep.com, 20 Dec. 2025

Garlic – antiviral and antibacterial properties; supports your body’s immune system. —Mélanie Nauche, Vogue, 20 Dec. 2025

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