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noun Common

bacteria

bak-TEER-ree-uh
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Bacteria (noun) means Microscopic single-celled organisms, some helpful and some capable of causing disease. Example: “Under the microscope, the students could see bacteria swimming in the drop of pond water.”

noun
1
Microscopic single-celled organisms, some helpful and some capable of causing disease.
"Under the microscope, the students could see bacteria swimming in the drop of pond water."
"Washing your hands helps remove harmful bacteria before you eat."
"Not all bacteria are dangerous — some in your gut actually help you digest food."

How to use bacteria

Learner’s notes

In plain EnglishTiny single-celled living things found almost everywhere, some of which cause illness and others of which are harmless or even beneficial.

Common mistake

"Bacteria" is technically plural — the singular form is "bacterium," though many people casually use "bacteria" for both.

Easily confused with
bacterium → virus →
Common pairings
harmful bacteria kill bacteria gut bacteria
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Word forms

Plural
bacteriae
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Fill the gap

Can you complete this real example?

Under the microscope, the students could see _____ swimming in the drop of pond water.

Etymology

From New Latin bactēria, taken from the Ancient Greek word for a small rod or staff, reflecting the rod-like shape of many bacteria.

Origin: Ancient Greek

Synonyms

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microbes germs microorganisms bugs pathogens bacterium

Related words

bugs bacterium

Rhymes for bacteria

Odia aria India Syria ataxia Latvia acacia LGBTQIA ectasia hryvnia begonia anaemia
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Frequently asked questions

What does “bacteria” mean?
The word “bacteria” means microscopic single-celled organisms, some helpful and some capable of causing disease. In plain terms, tiny single-celled living things found almost everywhere, some of which cause illness and others of which are harmless or even beneficial.
How do you pronounce “bacteria”?
“Bacteria” is pronounced bak-TEER-ree-uh (/bækˈtɪɹ.i.ə/ in IPA).
How do you use “bacteria” in a sentence?
Here is “bacteria” used in a sentence: “Washing your hands helps remove harmful bacteria before you eat.”
What part of speech is “bacteria”?
“Bacteria” is a noun.
Where does the word “bacteria” come from?
The word “bacteria” comes from Ancient Greek. From New Latin bactēria, taken from the Ancient Greek word for a small rod or staff, reflecting the rod-like shape of many bacteria.
Is “bacteria” a common word?
“Bacteria” is a fairly common word in modern English.
What is the difference between bacteria and viruses?
Bacteria are microscopic single-celled organisms, some helpful and some capable of causing disease, and they can live and reproduce on their own. Viruses are much smaller and cannot reproduce without infecting a host cell, which is a key biological difference between the two.
Is it bacteria or bacterium for a single organism?
Bacteria is the plural form, so one organism is a bacterium. A common mistake is treating bacteria as singular, as in "a bacteria," when the correct singular is bacterium.
Are all bacteria harmful?
No. Bacteria are single-celled organisms that include both helpful and harmful types. Many are beneficial, such as those aiding digestion, while only some are capable of causing disease.
Should bacteria take a singular or plural verb?
In careful writing, bacteria is plural and takes a plural verb, as in "the bacteria are growing." Because bacterium is the singular, using a singular verb with bacteria is generally considered incorrect.

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