What term refers to a deficiency or impairment in the immune system?

Immunodeficiency is the correct term used to describe a deficiency or impairment in the immune system. This condition occurs when the immune system's ability to fight infections and diseases is compromised, which can result from various factors including genetic conditions, malnutrition, certain medical treatments, or infections such as HIV. Individuals with immunodeficiency may experience recurrent illnesses or have difficulty combating infections that a healthy immune system would normally manage effectively.

In contrast, autoimmunity refers to a condition where the immune system mistakenly attacks the body's own cells, tissues, or organs, which is not a deficiency but rather a misdirected immune response. Infection involves the invasion of pathogens like bacteria or viruses into the body, prompting an immune response, rather than indicating a state of impaired immunity. Lastly, inflammation is a natural part of the immune response characterized by redness, heat, swelling, and pain as the body fights off infections or heals injuries; it does not imply a deficiency in the immune system. Therefore, immunodeficiency most accurately captures the essence of the impairment described in the question.