HIV

noun

ˌāch-ˌī-ˈvē 

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

Most of the more than 200 HIV cases in the region are connected to Mass and Cass drug injection, Ojikutu said, adding that the number would be higher without the city’s harm reduction approach. —Gayla Cawley, Boston Herald, 23 Sep. 2025

For 19 years, its dedicated staff and steadfast supporters have provided vital care to over 100,000 young people across southern Africa, including young people living with HIV/AIDS and those facing mental health challenges. —Stephanie Petit, PEOPLE, 23 Sep. 2025

In addition to age (65 and up), factors that increase the risk of severe COVID include chronic conditions like diabetes, HIV, and heart, lung, or kidney disease; being overweight or having obesity; and behaviors like smoking or physical inactivity. —Emily Kay Votruba, EverydayHealth.com, 23 Sep. 2025

Interruption to this regimen can reactivate hidden reservoirs of infected cells, leading to the rapid resurgence of HIV in a person’s blood and the development of drug-resistant variants. —New Atlas, 20 Sep. 2025

Word History

First Known Use

1986, in the meaning defined at sense 1

Phrases Containing HIV

• anti-HIV

Kids Definition

HIV

noun

ˌāch-ˌī-ˈvē 

: 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

HIV

noun

ˌā-ˌchī-ˈvē 

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