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

Like humans, plants have an immune system that protects them against attacks from pathogens like fungi. —Lily Peck, The Conversation, 17 Feb. 2026

Inflammation is a natural immune response, but chronic inflammation can actually suppress your immune system. —Lauren Manaker, SELF, 17 Feb. 2026

For a daily dose of immune system support, take two supplements per serving. —Bestreviews, Chicago Tribune, 17 Feb. 2026

Gut health is linked to digestion, skin, mood, and immune system function. —Rena Goldman, Health, 17 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