medical definition of immune
immune. 1. being highly resistant to a disease because of the formation of humoral antibodies or the development of immunologically competent cells, or both, or as a result of some other mechanism, as interferon activities in viral infections.ypersensitivity is the result of an overreaction to substances entering the body. Examples of this kind of inappropriate immune response include hay fever, drug and food allergies, extrinsic asthma, serum sickness, and anaphylaxis.