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

Food allergies occur when the body's immune system reacts to certain proteins in food. —Kristan Hawkins, Newsweek, 7 Feb. 2025

The greater the mutation, the less likely that your immune system will recognize and fight back against the disease. —Alexandra M. Lord, The Conversation, 6 Feb. 2025

However, the fact that researchers did not find such diminished protection against severe, deadly COVID-19 suggests that the evasion is likely targeting only certain components of our immune system. —Ars Technica, 6 Feb. 2025

Boost Immune System Jamu may be particularly helpful this time of year due to its effects on the immune system. —Maggie O'Neill, Verywell Health, 5 Feb. 2025

Word History

First Known Use

circa 1919, in the meaning defined above

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