1
: either of two retroviruses (species Human immunodeficiency virus 1 and 2 of the genus Lentivirus) 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

compare 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 world's largest government foreign aid agency, USAID saved millions of lives over the decades—particularly in Africa—through programs targeting crises such as HIV/AIDS, malaria, and maternal and child mortality. Thomas G. Moukawsher, MSNBC Newsweek, 25 Apr. 2025 In the 1980s, activists protested the CDC’s case definition of HIV/AIDS, which was too narrow to include many women with the condition. Scott Braunstein, Forbes.com, 24 Apr. 2025 Advocates and stakeholders raised the alarm when several branches of key federal HIV offices were effectively eliminated by HHS layoffs. Joseph Choi, The Hill, 23 Apr. 2025 In 2001, Rhyne died from complications related to HIV, per the outlet. Jordana Comiter, People.com, 22 Apr. 2025 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

Browse Nearby Words

Cite this Entry

“HIV.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/HIV. Accessed 29 Apr. 2025.

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 (species Human immunodeficiency virus 1 and 2 of the genus Lentivirus) 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

compare hiv-1, hiv-2
2
: the infection or disease caused by HIV
Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!