bacterium
B2Formal / Scientific
Definition
Meaning
A microscopic single-celled organism, often causing disease or involved in fermentation and decay.
The singular form of 'bacteria,' used in formal and scientific contexts; more generally, any prokaryotic microorganism (though excluding archaea).
Linguistics
Semantic Notes
'Bacterium' is a singular, count noun; 'bacteria' is its plural. In non-technical contexts, 'bacteria' is often used as a mass noun, but strict usage maintains the singular/plural distinction.
Dialectal Variation
British vs American Usage
Differences
No major differences in meaning or usage. In both dialects, 'bacterium' is the formal singular, but in casual speech, 'bacteria' is often used for both singular and plural.
Connotations
Identical; strongly associated with science, medicine, hygiene, and pathology.
Frequency
Used with similar frequency in scientific/technical contexts in both dialects. 'Bacteria' is significantly more common in everyday language.
Vocabulary
Collocations
Grammar
Valency Patterns
The bacterium [VERB] (e.g., The bacterium multiplies rapidly).A [ADJ] bacterium (e.g., a virulent bacterium).Bacterium of [NOUN] (e.g., bacterium of the genus Streptococcus).Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “Not applicable. The word is technical and does not feature in idiomatic expressions.”
Usage
Context Usage
Business
Rare, except in pharmaceutical, biotech, or food safety industries (e.g., 'The new process eliminates the target bacterium.').
Academic
Common in biology, medicine, microbiology papers and lectures (e.g., 'Each bacterium was cultured separately.').
Everyday
Very rare; 'bacteria' or 'germs' are preferred (e.g., 'I know there's a bacterium causing this, but I can't remember its name.').
Technical
Standard, precise term in scientific writing and discourse to refer to a single organism (e.g., 'The plasmid was inserted into the host bacterium.').
Examples
By Part of Speech
verb
British English
- Not applicable as a verb.
American English
- Not applicable as a verb.
adverb
British English
- Not applicable as an adverb.
American English
- Not applicable as an adverb.
adjective
British English
- The bacterial load was measured.
- It was a bacterium-free environment.
American English
- They studied the bacterial colony.
- A bacterium-specific antibiotic was used.
Examples
By CEFR Level
- You need to wash your hands to get rid of bad bacterium.
- A very small bacterium can make you ill.
- The doctor said a specific bacterium was causing the infection.
- Under the microscope, you can see a single bacterium.
- Researchers have identified the bacterium responsible for the outbreak.
- Each bacterium divides to form two identical cells.
- The novel bacterium exhibits unprecedented antibiotic resistance.
- The plasmid was successfully conjugated into the recipient bacterium.
Learning
Memory Aids
Mnemonic
Think: 'A bacterium is to bacteria as a datum is to data.' Both are Latin-derived singular forms ending in '-um.'
Conceptual Metaphor
BACTERIA ARE INVADERS / BACTERIA ARE FACTORIES (e.g., 'The bacterium invaded the tissue.' / 'The bacterium synthesises the enzyme.').
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'бактерия' (bakteriya) which is feminine in Russian; 'bacterium' is grammatically neutral in English.
- Avoid using 'bacteria' as a singular noun in formal writing; Russian often uses the plural form 'бактерии' (bakterii) for general concepts.
Common Mistakes
- Using 'bacteria' as a singular noun in formal writing (e.g., 'A bacteria was found...').
- Mispronouncing the '-ium' ending as '-iam'.
- Confusing 'bacterium' (living cell) with 'virus' (non-living infectious agent).
Practice
Quiz
What is the primary register for the word 'bacterium'?
FAQ
Frequently Asked Questions
'Bacterium' is the singular noun referring to one such organism. 'Bacteria' is the plural form. In non-scientific language, 'bacteria' is often used as a mass noun for both singular and plural concepts.
In strict, formal, or scientific English, yes, it is considered incorrect. You should say 'a bacterium' or 'a bacterial species'. However, 'a bacteria' is common in informal speech.
No, the word 'bacterium' itself is neutral. While some are pathogenic (harmful), many are essential for human health (e.g., gut flora), digestion, and environmental processes like decomposition.
It follows the Latin pattern: '-ium' -> '-ia'. Similar examples are 'datum/data', 'medium/media', 'criterion/criteria'. Remember: 'One bacterium, two bacteria'.