Autoimmune/ˌɔːtəʊɪˈmjuːn/ Definition 1 of 1Pro Tip 1/3Medical Condition Used to describe illnesses where the immune system mistakenly attacks healthy body parts. Rheumatoid arthritis is an autoimmune condition. Pro Tip 2/3Specialist Vocabulary Commonly used by healthcare professionals, but also understood by general public. Autoimmune diseases can be managed with proper treatment. Pro Tip 3/3Non-Contagious 'Autoimmune' refers to a body's self-response, not an illness you catch from others. Unlike the flu, autoimmune disorders are not contagious.