Immunodeficient

In medicine, immunodeficiency (or immune deficiency) is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Most cases of immunodeficiency are either congenital or acquired. A person who has an immunodeficiency is said to be immunocompromised. An immunocompromised person is very vulnerable to opportunistic infections. Boys more often than girls can have immune deficiency. Mostly immune deficiency is recognized in the early ages unless it is an acquired immune deficiency.
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Immunodeficient A condition in which the body's immune response is damaged, weakened, or is not functioning properly. Mentioned in: AIDS [more]Immunodeficient - Community and Resources

Lacking immunity and so susceptible to infection.