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noun Common

bacteria

bak-TEER-ree-uh

Bacteria (noun) means Microscopic single-celled organisms, some helpful and some capable of causing disease. Example: “Washing your hands helps remove harmful bacteria before you eat.”

noun
1
Microscopic single-celled organisms, some helpful and some capable of causing disease.
"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
Common pairings
harmful bacteria kill bacteria gut bacteria

Word forms

bacteriae plural

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Test yourself on “bacteria” A quick quiz — meaning, synonyms & usage

Fill the gap

Can you complete this real example?

Washing your hands helps remove harmful _____ before you eat.

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

microbes germs microorganisms bugs pathogens

Related words

Rhymes for bacteria

See all rhymes for bacteria →

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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