Bacteria (/ b æ k ˈ t ɪər i ə / ⓘ; sg.: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms .

The meaning of BACTERIUM is any of a domain (Bacteria) of chiefly round, spiral, or rod-shaped single-celled prokaryotic microorganisms that typically live in soil, water, organic matter, or the bodies of plants and animals, that make their own food especially from sunlight or are saprophytic or parasitic, are often motile by means of flagella ...

Bacteria are microscopic living organisms that have only one cell. The word for just one is “bacterium.” Millions (if not billions) of different types of bacteria can be found all over the world, including in your body. They’re on your skin and in your airways and mouth.

Feb 28, 2025 · bacteria, any of a group of microscopic single-celled organisms that live in enormous numbers in almost every environment on Earth, from deep-sea vents to deep below Earth’s surface to the digestive tracts of humans.

Bacteria are single-celled microorganisms that differ from all other organisms (the eukaryotes) in lacking a true nucleus and organelles such as mitochondria, chloroplasts, and lysosomes.

BACTERIUM definition: 1. a type of very small organism that lives in air, earth, water, plants, and animals, often one…. Learn more.

Oct 4, 2019 · Bacteria are single-celled microorganisms with prokaryotic cells, which are single cells that do not have organelles or a true nucleus and are less complex than eukaryotic cells. Bacteria with a capital B refers to the domain Bacteria, one of the three domains of life.

Jul 24, 2022 · Bacteria are defined as organisms that are microscopic, unicellular, independently reproducing, and mostly free-living. Bacteria are ubiquitous in nature. They are structurally simple but functionally complex organisms that form the basis of all life on earth. Most bacteria, barring a few, are beneficial for their environment.

Feb 12, 2019 · Bacteria are microscopic, single-celled organisms that exist in their millions, in every environment, both inside and outside other organisms. Some bacteria are harmful, but most serve a useful...

May 14, 2024 · Bacteria, a singular bacterium, is derived from the Ancient Greek word “backērion” meaning “cane”, as the first bacteria observed were bacilli. The study of ‘Bacteria’ is called ‘Bacteriology’; a branch of ‘Microbiology’.