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

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.

From 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.

From Los Angeles Times

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

From Salon

The product is made from small, purified doses of botulinum toxin, produced by the bacterium Clostridium botulinum.

From BBC

Pneumonic plague is a severe lung infection caused by the Yersinia pestis bacterium.

From BBC

Related Words

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