- a disease of the immune system characterized by increased susceptibility to opportunistic infections, as pneumocystis carinii pneumonia and candidiasis, to certain cancers, as Kaposi's sarcoma, and to neurological disorders: caused by a retrovirus and transmitted chiefly through blood or blood products that enter the body's bloodstream, especially by sexual contact or contaminated hypodermic needles.
- acquired immune (or immuno-)deficiency syndrome: a condition, caused by a virus, in which certain white blood cells (lymphocytes) are destroyed, resulting in loss of the body's ability to protect itself against disease. AIDS is transmitted by sexual intercourse, through infected blood and blood products, and through the placenta
