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Definitions

bacterium

[bak-teer-ee-uhm] / bækˈtɪər i əm /
NOUN
cell
Synonyms
STRONGEST
egg germ unit
STRONG
corpuscle embryo follicle microorganism spore utricle vacuole
WEAK
cellule haematid
NOUN
ferment
Synonyms
STRONG
bacteria barm ebullition enzyme leaven leavening mold seethe simmer yeast
WEAK
fermentation agent
Antonyms
WEAK
calm contentedness happiness peace pleasure
NOUN
germ
Synonyms
STRONGEST
antibody bug disease microbe microorganism pathogen virus
WEAK
parasite what's going around
NOUN
microbe
Synonyms
STRONGEST
bacillus bug germ microorganism pathogen virus
STRONG
crud plague
NOUN
microorganism
Synonyms
STRONGEST
microbe pathogen virus
STRONG
bug disease
WEAK
disease-causing agent parasite

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Flea-borne typhus is caused by the bacterium Rickettsia typhi.

From Los Angeles Times • Apr. 3, 2026

An initial genetic analysis of the bacterium causing the outbreak was concluded on Thursday.

From BBC • Mar. 20, 2026

Does the explanation for its scale and speed lie solely in the bacterium itself or did other factors play a role?

From BBC • Mar. 20, 2026

Even short exposure to the bacterium increased levels of a protein called PKcs, which was linked to greater cancer cell movement, invasion, stem-like traits, and resistance to chemotherapy.

From Science Daily • Mar. 19, 2026

This bacterium actually kills by poisoning rather than by disease.

From "Silent Spring" by Rachel Carson