Oxford Dictionary English immune system noun noun BrE BrE//ɪˈmjuːn sɪstəm// ; NAmE NAmE//ɪˈmjuːn sɪstəm// Add to my wordlistjump to other results the system in your body that produces substances to help it fight against infection and diseaseSee immune system in the Oxford Learner's Dictionary of Academic EnglishSee immune system in the Oxford Advanced American DictionaryCheck pronunciation: immune system oxfordlearnersdictionaries.com