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 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

Kevin Monsalvo, 26, has followed in the footsteps of Granados and said things are different for him since he learned more about the organism threatened with extinction.

From Barron's • May 7, 2026

The team's genome and transcriptome analysis also identified suppressor tRNA genes that match the reassigned codons, supporting the conclusion that the organism truly reads these former stop signals as amino acids.

From Science Daily • May 7, 2026

This organism is widely studied because it shares many basic biological features with more complex life forms, including humans.

From Science Daily • Apr. 12, 2026

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

The first living things were not anything so complex as a one-celled organism, already a highly sophisticated form of life.

From "Cosmos" by Carl Sagan

Related Words

• animal
• creature
• structure