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

The death rate is even higher for children, whose immune systems are less developed. — Durrie Bouscaren, NPR, 10 Sep. 2026

Listeria monocytogenes can cause listeriosis, a serious infection that can be especially dangerous for older adults, people with weakened immune systems, pregnant individuals and newborns. — Angela Rodriguez, Sacbee.com, 9 Sep. 2026

An infection from the bacteria can lead to death in young children, the elderly and those with weak immune systems if they are infected. — Julia Gomez, USA Today, 9 Sep. 2026

Only the machinations of ABC/Disney and my own rogue immune system have kept me from writing recaps here on Vulture over the last 11 years. — Ali Barthwell, Vulture, 4 Sep. 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