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-2
2
: 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

Examples of HIV in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The group arrives at the lake during mosquito season, triggering a buzz of paranoia amongst the local lake residents, fearing that Davey’s friends will expose them to contracting HIV from a mosquito bite. Georg Szalai, HollywoodReporter, 6 July 2026 Philip Lewis, a relationship therapist specializing in gay men's mental health, says finding a community can be one of the most beneficial things when faced with a diagnosis of HIV or any chronic health condition. Charles Trepany, USA Today, 2 July 2026 Both would become heavily involved in advocacy for HIV/AIDS research. Rance Collins, Entertainment Weekly, 2 July 2026 Jeff Graham, of the LGBTQ+ rights organization Georgia Equality, said testing and prevention efforts at the community level have been crucial to the progress in reducing new HIV cases. Tamar Hallerman, AJC.com, 1 July 2026 See All Example Sentences for HIV

Word History

First Known Use

1986, in the meaning defined at sense 1

Time Traveler
The first known use of HIV was in 1986

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Cite this Entry

“HIV.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/HIV. Accessed 7 Jul. 2026.

Kids Definition

: any of a group of viruses that infect and destroy helper T cells causing the marked reduction in their numbers that is diagnostic of AIDS

Medical Definition

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.

called also AIDS virus, human immunodeficiency virus

see also hiv-1, hiv-2
2
: the infection or disease caused by HIV
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