germ

American  

[jurm] / dʒɜrm /

noun

1. a microorganism, especially when disease-producing; microbe.

2. a bud, offshoot, or seed.

3. the rudiment of a living organism; an embryo in its early stages.

4. the initial stage in development or evolution, as a germ cell or ancestral form.

   Synonyms:

   seed, rudiment, bud, root, spark

5. something that serves as a source or initial stage for subsequent development.

   the germ of an idea.

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adjective

1. Pathology. of, relating to, or caused by disease-producing germs.

germ British  

/ dʒɜːm /

noun

1. a microorganism, esp one that produces disease in animals or plants

2. (often plural) the rudimentary or initial form of something

   the germs of revolution

3. a simple structure, such as a fertilized egg, that is capable of developing into a complete organism

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germ Scientific  

/ jûrm /

1. A microscopic organism or agent, especially one that is pathogenic, such as a bacterium or virus.

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Usage

The terms germ and microbe have been used to refer to invisible agents of disease since the nineteenth century, when scientists introduced the germ theory of disease, the idea that infections and contagious diseases are caused by microorganisms. Microbe, a shortening and alteration of microorganism, comes from the Greek prefix mikro–, “small,” and the word bios, “life.” Scientists no longer use the terms germ and microbe very much. Today they can usually identify the specific agents of disease, such as individual species of bacteria or viruses. To refer generally to agents of disease, they use the term pathogen, from the Greek pathos, “suffering,” and the suffix –gen, “producer.” They use microorganism to refer to any unicellular organism, whether disease-causing or not.

Other Word Forms

• germless adjective
• germlike adjective

Etymology

Origin of germ

1400–50; late Middle English < Middle French germe < Latin germen shoot, sprout, by dissimilation from *genmen, equivalent to gen- ( genitor, genus ) + -men resultative noun suffix)

Explanation

A germ is a tiny life form that spreads disease. Germs are also small things that grow into larger things — whether animals, plants, or ideas. Germ is not a technical term, but you've probably heard it used in reference to tiny organisms (such as bacteria) that cause disease. A germ is also any small structure, such as a fertilized egg, that grows into something larger. A seed that grows into a plant is a germ. In some cases, you can talk about ideas as germs. The inspiration for a book or movie can be described as the germ of the project. Germs are small, but they start big things.

Example Sentences

According to Public Health Wales, Staph infection is a bacterial infection caused by staphylococcus - a germ that lives in the nose of one in three people.

From BBC • Mar. 28, 2026

"Between 10-24 per cent of the population unknowingly carry this germ at the back of their throats usually without any harm," said Lee.

From Barron's • Mar. 19, 2026

To test their effects, scientists introduced these bacteria into germ free mice that lacked normal serotonin levels.

From Science Daily • Mar. 13, 2026

The author appreciates what a terrific advance modern germ theory represents, but she also recognizes its tendency to generate absurd excesses.

From The Wall Street Journal • Jan. 23, 2026

They are also the grandfathers of the germ theory of disease, and therefore of much of modern medicine.

From "Cosmos" by Carl Sagan

Related Words

• antibody
• bacterium
• bug
• disease
• microbe
• microorganism
• pathogen
• virus