organism

American  

[awr-guh-niz-uhm] / ˈɔr gəˌnɪz əm /

noun

1. a form of life composed of mutually interdependent parts that maintain various vital processes.

2. a form of life considered as an entity; an animal, plant, fungus, protistan, or moneran.

3. any organized organized body or system conceived of as analogous to a living being.

   the governmental organism.

4. any complex thing or system having properties and functions determined not only by the properties and relations of its individual parts, but by the character of the whole that they compose and by the relations of the parts to the whole.

   Synonyms:

   structure, entity, network, organization

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organism British  

/ ˈɔːɡəˌnɪzəm /

noun

1. any living biological entity, such as an animal, plant, fungus, or bacterium

2. anything resembling a living creature in structure, behaviour, etc

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organism Scientific  

/ ôr′gə-nĭz′əm /

1. An individual form of life that is capable of growing, metabolizing nutrients, and usually reproducing. Organisms can be unicellular or multicellular. They are scientifically divided into five different groups (called kingdoms) that include prokaryotes, protists, fungi, plants, and animals, and that are further subdivided based on common ancestry and homology of anatomic and molecular structures.

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Other Word Forms

• organismal adjective
• organismally adverb
• organismic adjective
• organismically adverb
• superorganism noun

Etymology

Origin of organism

First recorded in 1655–65; organ + -ism

Explanation

An organism is a living thing that can function on its own. That includes your pet guppy, the tree in your backyard, and — of course — you. While the word organism typically indicates an actual living thing, you can also use organism to refer to anything that acts or functions like a living thing. For example, the social scene at a high school might be described as "a social organism" because it seems to have a mind of its own — like a living thing or even a vicious animal, depending on where one falls on the popularity scale.

Example Sentences

Grace is sent into space on a one-way mission to stop the spread of an energy-consuming organism called Astrophage, which threatens to create a new Ice Age on Earth.

From The Wall Street Journal • Apr. 3, 2026

She added that the drugs did not provide effective coverage against a Gram-positive organism, which was the most likely pathogen causing the infection.

From BBC • Mar. 11, 2026

To build their system, the researchers used the budding yeast Saccharomyces cerevisiae, an organism widely used both in brewing and scientific research.

From Science Daily • Mar. 9, 2026

Genetic analysis confirmed that the organism represents not only a newly identified species but also an entirely new genus.

From Science Daily • Mar. 6, 2026

Question for the Notebook: When does the young human organism get a grasp of time?

From "The Evolution of Calpurnia Tate" by Jacqueline Kelly

Related Words

• animal
• creature
• structure