bacterium

[bak-teer-ee-uhm]

noun

1. singular of bacteria.

bacterium

/ bækˈtɪərɪəm /

noun

1. the singular of bacteria

bacterium

plural

bacteria 

1. Any of a large group of one-celled organisms that lack a cell nucleus, reproduce by fission or by forming spores, and in some cases cause disease. They are the most abundant lifeforms on Earth, and are found in all living things and in all of the Earth's environments. Bacteria usually live off other organisms. Bacteria make up most of the kingdom of prokaryotes (Monera or Prokaryota), with one group (the archaea) sometimes classified as a separate kingdom.

2. See also archaeon prokaryote

Usage

It is important to remember that bacteria is the plural of bacterium, and that saying a bacteria is incorrect. It is correct to say The soil sample contains millions of bacteria, and Tetanus is caused by a bacterium.

Word History and Origins

Origin of bacterium¹

1840–50; < New Latin < Greek baktḗrion, diminutive of baktēría staff; akin to báktron stick, Latin baculum, bacillum

Example Sentences

It is rare for food contaminated by listeria, a bacterium, to cause a very serious infection, known as listeriosis.

Read more on BBC

Beyond the vast knowledge accumulated about its genetics and the tools that make it easy to engineer, the bacterium grows quickly and predictably on a wide variety of substrates.

Read more on BBC

Animals live in much greater concentrations in rural areas, where they are in closer proximity to other creatures and habitats, making it easier for the bacterium to thrive, Swartzberg said.

Read more on Los Angeles Times

The disease is caused by the bacterium Yersinia pestis and is most commonly spread to humans by bites from infected fleas, according to El Dorado County health officials.

Read more on Los Angeles Times

Listeria is a microscopic bacterium often found in deli meats, hot dogs, and soft cheeses.

Read more on Salon

Related Words

• antibody 
• bug 
• disease 
• microbe 
• microorganism 
• pathogen 
• virus