norovirus

noun

nor·​o·​vi·​rus ˈnȯr-ə-ˌvī-rəs 

plural noroviruses

: any of a genus (Norovirus) of small, round, single-stranded RNA viruses that includes a single species (N. norwalkense) with various strains causing gastroenteritis in people and animals (such as cows, pigs, and dogs)

People spread the virus by eating food or drinking liquids that are contaminated with norovirus, touching surfaces or objects contaminated with norovirus and then touching their mouth or having direct contact with another person who is infected.

—Cherie Black

Note: In people, noroviruses cause gastroenteritis marked chiefly by sudden onset diarrhea, vomiting, nausea, and abdominal cramps.

see norwalk virus

Examples of norovirus in a Sentence

Recent Examples on the Web

Last year, WasteWaterSCAN data showed norovirus concentrations started to increase in October and peaked in February. —Mary Walrath-Holdridge, USA Today, 16 Dec. 2025

While California is not one of the reporting states, CDC data shows a sharp increase in positive norovirus tests throughout the month of November for the entire western United States. —Hannah Poukish, Sacbee.com, 15 Dec. 2025

This latest incident adds to a growing number of norovirus outbreaks reported on cruise ships this year. —Kelly McGreal , Ashley J. Dimella, FOXNews.com, 8 Dec. 2025

What To Know For the week of November 15, about 13 percent of norovirus tests were positive, double the rate from around three months earlier, according to the CDC's NoroSTAT program. —Jasmine Laws, MSNBC Newsweek, 4 Dec. 2025

Word History

Etymology

New Latin, from English Norwalk virus + New Latin -o- + virus

First Known Use

2002, in the meaning defined above

Rhymes for norovirus

• antivirus
• herpesvirus
• parvovirus
• reovirus
• retrovirus
• rhinovirus
• rotavirus
• adenovirus
• baculovirus
• coronavirus
• enterovirus
• poliovirus

Medical Definition

norovirus

noun

nor·​o·​virus ˌnȯr-ō-ˈvī-rəs 

1

Norovirus : a genus of caliciviruses that includes a single species (Norovirus norwalkense) with various strains causing gastroenteritis in people and animals (such as cows and dogs)

2

: any virus of the genus Norovirus

Norovirus can be transmitted person-to-person (via the fecal-oral route) and spread through contaminated airborne droplets, food, water, environmental surfaces, and fomites.

—The Journal of the American Medical Association

Note: In people, noroviruses cause gastroenteritis marked chiefly by sudden onset, diarrhea, vomiting, nausea, and abdominal cramps.

see norwalk virus