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 first cleanser removes sweat, sunscreen, deodorant, excess oil, and odor-causing bacteria and the second provides another level of cleansing while restoring moisture, supporting the skin barrier or delivering an active ingredient,” Gohara said.
From The Wall Street Journal ● Sep. 11, 2026
Public health officials across Los Angeles County also urge people to avoid swimming in the ocean through Wednesday because of potential bacteria spikes from rain Sunday and Monday.
From Los Angeles Times ● Sep. 8, 2026
The discovery could change how researchers connect gut bacteria with disease.
From Science Daily ● Sep. 7, 2026
Across Los Angeles County, public health officials urged beachgoers to avoid swimming in the ocean through Wednesday because of potential bacteria spikes from the rain.
From Los Angeles Times ● Sep. 7, 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 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 naturally live in the human body and influence both health and disease.
From Science Daily ● Mar. 21, 2026
Bacteria are also "promiscuous," easily exchanging genetic material.
From Salon ● Apr. 24, 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
Infection with this bacterium is a known risk factor for gastric cancer.
From Science Daily ● Sep. 10, 2026
Coauthor Associate Professor Debnath Ghosal from The University of Melbourne says directly capturing an interaction between an Asgard archaeon and a bacterium is particularly significant.
From Science Daily ● Sep. 3, 2026
It is more unusual to see an outbreak like this linked to one specific stain of the bacterium affecting many people at one time.
From BBC ● Aug. 18, 2026
Just this month, tularemia, also known as rabbit fever and caused by a bacterium in ticks and deer flies, was detected in people living on Long Island.
From Los Angeles Times ● Aug. 16, 2026
Reed favored the idea that a bacterium, first identified by Italian scientists and usually found in swamps, was the culprit.
From "An American Plague: The True and Terrifying Story of the Yellow Fever Epidemic of 1793" by Jim Murphy
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.
