Plural word for bacteria Bacteria is the plural form of the singular bacterium. Because microscopic bacterium is most often found in multiples, the plural form bacteria is more commonly used. The plurals of several other singular words ending in -um are also formed this way, such as memorandum/memoranda and curriculum/curricula. The irregular noun bacterium’s plural derives directly from its original pluralization in Latin and Greek. Bacteria is sometimes treated as a singular collective noun. However, this is not standard in English, and bacteria should be treated as a plural form.
Some bacteria are beneficial to humans (for example, those that live in the stomach and aid digestion), and some are harmful (for example, those that cause disease).
First recorded in 1860–65; from New Latin, from Greek baktḗria, plural of baktḗrion, diminutive of baktēría “staff, cane”; see origin at bacterium
First recorded in 1860–65; from New Latin; see origin at bacteria ( def. )
Bacteria are microscopic living organisms, usually one-celled, that can be found everywhere. They can be dangerous, such as when they cause infection, or beneficial, as in the process of fermentation (such as in wine) and that of decomposition. In 1676, Anton Van Leeuwenhoek first observed bacteria through a microscope and called them “animalcules.” In 1838, the German Naturalist Christian Gottfried Ehrenberg called them bacteria, from the Greek baktḗria, meaning "little stick." An apt word, as the first observed bacteria were shaped like rods, although bacteria can also be spiral or spherical in shape. A grammar note: The word bacteria is the plural form of "bacterium" and so should be written as plural, as in "Many bacteria are harmless."
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The fever is not harmful, but it can make babies feel crummy as their body is building up antibodies against viruses and bacteria.
From Los Angeles Times ● Jul. 28, 2026
Only male mosquitoes – infected with the naturally occurring bacteria Wolbachia – are released.
From BBC ● Jul. 27, 2026
In particular, they’re examining how bacteria from diseased gums, and the immune response they trigger, may contribute to conditions including heart disease, diabetes, cognitive decline, arthritis, respiratory disease and chronic liver disease.
From The Wall Street Journal ● Jul. 26, 2026
Inulin is a prebiotic, which means it provides nourishment for beneficial gut bacteria.
From Science Daily ● Jul. 25, 2026
When bacteria switched from glucose to lactose consumption, they induced specific lactose-digesting enzymes.
From "The Gene" by Siddhartha Mukherjee
Bacteria that cause gum disease may do more than damage your teeth.
From Science Daily ● Jul. 13, 2026
Bacteria can also infect wounds where screwworm maggots are present and may cause an infection that can lead to symptoms like fever or chills.
From Los Angeles Times ● Jun. 6, 2026
Bacteria and viruses can hide inside amoebae, where they may be shielded from disinfectants and other treatment methods.
From Science Daily ● Jun. 6, 2026
Bacteria such as E. coli and Salmonella, or parasites like Cryptosporidium and Giardia, also cause severe diarrhea that can lead to dangerous levels of dehydration.
From Salon ● Jan. 27, 2025
Bacteria have a lot more to do than viruses.
From "Cosmos" by Carl Sagan
Some governments also use Wolbachia, a naturally occurring bacterium found in about half of all insect species, to curb the spread of mosquito-borne diseases like dengue.
From BBC ● Jul. 23, 2026
The team first identified a major contributor to the disease: an overgrowth of the bacterium Clostridium perfringens, which generates ammonia inside the gut.
From Science Daily ● Jul. 11, 2026
The New York company said in a statement that so far its product had not tested positive for the bacterium Clostridium botulinum.
From Los Angeles Times ● Jun. 14, 2026
Only two decades ago, it was widely doubted by specialists that the Black Death was caused by the bacterium Yersinia pestis, the agent of the bubonic plague.
From The Wall Street Journal ● Jun. 12, 2026
In the early 1920s, Griffith, a medical officer at the British Ministry of Health, began to investigate a bacterium named Streptococcus pneumoniae or pneumococcus.
From "The Gene" by Siddhartha Mukherjee
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
