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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Some of the cases date back a year, but all involve bacteria that are almost genetically identical, suggesting a common food source.
From BBC ● Aug. 27, 2026
On average, about 1 million bacteria live on every patch of skin roughly the size of a pencil eraser.
From Science Daily ● Aug. 25, 2026
The study drew on experiments involving mice, cells, bacteria and human samples.
From Science Daily ● Aug. 24, 2026
Broad-spectrum antibiotics are designed to act against many different types of bacteria, which is why they can produce substantial changes in the gut microbial community.
From Science Daily ● Aug. 24, 2026
“I know that’s a real lot of bacteria in one hot sweaty room,” I tell Guillermo.
From "I'll Give You the Sun" by Jandy Nelson
Bacteria found in soil and water are essential parts of natural ecosystems, and some species are capable of processing substances that can be harmful to humans and other organisms.
From Science Daily ● Aug. 9, 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 survive inside amoebae, shielded from disinfection processes that would normally eliminate them.
From Science Daily ● Jan. 25, 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 are the greatest of all at setting up joint enterprises, on which the lives of their hosts are totally dependent.
From "The Lives of a Cell" by Lewis Thomas
And in April, Rickettsia, a rare but deadly tick-borne bacterium, was found in a person living in Sonoma County.
From Los Angeles Times ● Aug. 16, 2026
According to the researchers, the discovery also demonstrates the remarkable adaptability of Treponema pallidum, the bacterium responsible for treponemal diseases.
From Science Daily ● Aug. 12, 2026
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
At least for a while, though, as long as the patient is still alive, the cholera bacterium profits from being massively broadcast into the water supplies of its next victims.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
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.
