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 bacteria makes it harder for the insects to spread the virus, rather than kill them off.
From BBC ● Jul. 23, 2026
"To find novel strains of these bacteria in a deep-diving whale species is intriguing."
From Science Daily ● Jul. 21, 2026
Because pygmy sperm whales are so difficult to study at sea, researchers still do not know how widespread the newly identified bacteria may be or how much they affect the animals over time.
From Science Daily ● Jul. 21, 2026
University students are particularly at risk because they mix with lots of new people, and the bacteria that causes meningitis is spread in similar ways to the common cold through sneezing and coughing.
From BBC ● Jul. 19, 2026
Touching your eyes, nose, or mouth is an easy way for bacteria and germs to get into the body.
From "The Miscalculations of Lightning Girl" by Stacy McAnulty
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 are remarkably adaptable, thriving in some of the harshest places on Earth, from boiling hot springs to deep freezes far below zero.
From Science Daily ● Feb. 21, 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, fungi, and algae are the principal agents of decay, reducing plant and animal residues to their component minerals.
From "Silent Spring" by Rachel Carson
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 detected DNA from Yersinia pestis, the bacterium responsible for plague, in 18 of 46 individuals studied.
From Science Daily ● Jun. 18, 2026
Infant botulism happens when swallowed spores from the bacterium infect a baby’s large intestine and make a toxin in it.
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
Following work performed in Germany by others, he discovered that the bacterium came in two strains.
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.
