# organism

/ˈɔɹɡəˌnɪzəm/ (US) · /ˈɔːɡənˌɪzəm/ (UK)

Source: https://englishreference.com/word/organism
Updated: 2026-06-20

## Senses

### 1. a living thing

noun · CEFR B2

any living thing, from a tiny germ to a giant whale.

For teachers: an individual living system, such as an animal, plant, fungus, or bacterium, capable of response to stimuli, reproduction, growth, and homeostasis.

- The pond is full of tiny organisms that you can only see with a microscope.
- Biologists are still discovering new marine organisms in the deepest parts of the ocean that survive without any sunlight.

Usage: Countable noun; often used in scientific or academic contexts rather than casual conversation.

### 2. a complex system

noun · CEFR C1 · Academic · Formal

a large system or organization that has many parts working together like a body.

For teachers: a complex structure or organization with interdependent parts whose functions are determined by their relation to the whole.

- The government is a massive organism that changes very slowly.
- The city functions as a social organism, where transport, housing, and commerce must remain in balance to ensure the health of the community.

Teaching tip: This is a metaphorical use; learners should use it when describing how different departments or sections of a large group interact.

## Examples

- The pond is full of tiny organisms that we cannot see.
- Scientists are studying how this specific organism survives in the extreme heat of deep-sea vents.
- Every organism within the ecosystem plays a vital role in maintaining the delicate balance of nutrient cycles and energy flow through the food web.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.