HIV
noun
1
: either of two retroviruses (Lentivirus humimdef1 and L. humimdef2) that infect and destroy helper T cells of the immune system and that when left untreated cause AIDS
Note: HIV retroviruses are transmitted through contact with blood, semen, rectal and vaginal fluids, or breast milk and typically cause flu-like symptoms during the acute phase of infection, but often cause few or no symptoms during the chronic phase of infection when treated with antiretroviral drugs.
… the longer people are infected with HIV and the more immune-deficient they become, the more readily they seem to pass HIV to others.—Robert R. Redfield et al.
Years of careful research have proven beyond doubt that the HIV virus causes AIDS, that antiretroviral drug treatment saves lives, and that the drug nevirapine is safe and effective in preventing the spread of HIV from mothers to their babies.—Richard Marlink et al.
called also AIDS virus, human immunodeficiency virus
see also hiv-1, hiv-22
: the infection or disease caused by HIV
Early symptoms of HIV develop in 50 to 90 percent of people who are infected, usually beginning two to four weeks after exposure. … Because the signs and symptoms of … HIV may be similar to other common illnesses, such as mononucleosis, most people do not initially realize that they have HIV.—Paul E. Sax
Cite this Entry
“HIV.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/HIV. Accessed 1 Sep. 2026.
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