immune system: Meaning and Definition of

immune' sys"tem

Pronunciation: [key]
— Anat. Anat.
  1. a diffuse, complex network of interacting cells, cell products, and cell-forming tissues that protects the body from pathogens and other foreign substances, destroys infected and malignant cells, and removes cellular debris: the system includes the thymus, spleen, lymph nodes and lymph tissue, stem cells, white blood cells, antibodies, and lymphokines.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.