Definition of AIDS
: a disease of the human immune system that is characterized cytologically especially by reduction in the numbers of CD4-bearing helper T cells to 20 percent or less of normal thereby rendering the subject highly vulnerable to life-threatening conditions (such as Pneumocystis carinii pneumonia) and to some (such as Kaposi's sarcoma) that become life-threatening and that is caused by infection with HIV commonly transmitted in infected blood especially during illicit intravenous drug use and in bodily secretions (such as semen) during sexual intercourse
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Merriam-Webster unabridged
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Time Traveler for AIDS
The first known use of AIDS was in 1982
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