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

For astronauts, these findings mean that long missions could weaken the blood and immune systems, potentially raising health risks, said Arun Sharma, a stem cell biologist and an associate professor of biomedical sciences at Cedars-Sinai Medical Center in California. —Jacopo Prisco, CNN Money, 5 Sep. 2025

Symptoms related to Listeria monocytogenes Listeria is especially harmful to people whose immune system is weakened or not fully developed but can also impact healthy individuals. —Julia Gomez, USA Today, 5 Sep. 2025

These multiple doses do not overwhelm a baby's immune system, the CDC says. —Mary Kekatos, ABC News, 4 Sep. 2025

Inflammatory Skin Conditions Inflammatory skin conditions like eczema (atopic dermatitis) and psoriasis develop due to an overactive immune system. —Lindsay Curtis, Health, 4 Sep. 2025

Word History

First Known Use

circa 1919, 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