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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Cooling systems can draw large volumes of municipal water, while mists from cooling towers can carry harmful bacteria.
From Barron's ● Nov. 5, 2026
Timing matters because bacteria can change their susceptibility to phages during an infection.
From Science Daily ● Nov. 5, 2026
The treatments use viruses individually selected to target the bacteria causing each patient's infection.
From Science Daily ● Nov. 5, 2026
It is understood the latest problem at the maternity hospital has been caused by chemical flushing aimed at dealing with the original issue of bacteria in the water system.
From BBC ● Nov. 4, 2026
The constant probing of the president's wound, insertions of tubes, and surgical incisions created plenty of opportunities for bacteria to enter Garfield's body.
From "Ambushed!" by Gail Jarrow
Bacteria in treated trees have dropped by at least 90%.
From The Wall Street Journal ● Sep. 19, 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 naturally live in the human body and influence both health and disease.
From Science Daily ● Mar. 21, 2026
Bacteria and viruses can survive inside amoebae, shielded from disinfection processes that would normally eliminate them.
From Science Daily ● Jan. 25, 2026
Bacteria perform a wide variety of actions beneficial to humans, from decomposing organic matter to leavening bread.
From "Phineas Gage" by John Fleischman
The building was handed over to the Belfast Trust in March 2024, but the discovery of the potentially dangerous pseudomonas bacterium in the water system and other problems has meant the hospital has remained closed.
From BBC ● Nov. 4, 2026
Because they are all “kissing cousins,” as Livieri puts it, they fail to express a protein that helps fight the bacterium behind the medieval Black Death.
From The Wall Street Journal ● Nov. 4, 2026
For nearly two decades, scientists have known that a common gut bacterium can produce a toxin that damages the colon and helps drive the formation of tumors.
From Science Daily ● Oct. 31, 2026
The bacterium that causes it still exists in parts of Africa and Asia, including Siberia.
From The Wall Street Journal ● Oct. 30, 2026
By some standards, it is about as smart as a grasshopper; by others, only as intelligent as a bacterium.
From "Cosmos" by Carl Sagan
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