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

La Jolla immunologist named distinguished fellow Michael Croft, a professor emeritus at the La Jolla Institute for Immunology, has been named a distinguished fellow of the American Association of Immunologists, considered one of the highest honors in the field of immune system research. —Noah Lyons, San Diego Union-Tribune, 24 Feb. 2026

Propolis, what bees use to insulate the walls of their hives to protect against outside germs, is brilliant for soothing sore throats, bolstering our immune systems, and protecting against free radicals. —Brianna Peters, Vogue, 23 Feb. 2026

Traditional vaccines prime the immune system for specific targets, such as a protein on a virus. —Tom Chivers, semafor.com, 23 Feb. 2026

This suggests that consuming tiger nuts or using their extracts may support the immune system and reduce the risk of certain infections. —Lana Barhum, Verywell Health, 23 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