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unicellular

American  
[yoo-nuh-sel-yuh-ler] / ˌju nəˈsɛl jə lər /

adjective

  1. having or consisting of a single cell.


unicellular British  
/ ˌjuːnɪˈsɛljʊlə /

adjective

  1. (of organisms, such as protozoans and certain algae) consisting of a single cell

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

unicellular Scientific  
/ yo̅o̅′nĭ-sĕlyə-lər /
  1. Having or consisting of a single cell.

  2. Compare multicellular


Other Word Forms

Etymology

Origin of unicellular

First recorded in 1855–60; uni- + cellular

Explanation

In biology, the adjective unicellular describes an organism that has only one single cell, like most kinds of bacteria. You're most likely to see the word unicellular in a biology textbook, where it is used to talk about microscopic, single-celled organisms. Many types of fungi are unicellular, as well as amoebas, bacteria, and other tiny creatures and plants. The word unicellular combines the Latin prefix meaning "one," uni, and the word cellular, which has the root word cella, "small room."

Keep Reading on Vocabulary.com

Vocabulary lists containing unicellular

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.

See Examples For:

The researchers also compared blood cells with unicellular organisms in an effort to identify possible single-celled ancestors.

From Science Daily May 27, 2026

Galdieria extract blue comes from a unicellular red algae, which is an organism that thrives in extreme marine and terrestrial environments, according to the National Institutes of Health.

From Los Angeles Times May 14, 2025

Though Jablonski is more bullish on the survival prospects of unicellular life, there is some comfort for the multicellular among us too.

From Salon Feb. 25, 2025

To do this, the researchers surveyed Golgi structure in representatives of various animal taxa and closely related unicellular eukaryotes.

From Science Daily Feb. 29, 2024

A very small drop of chloroform introduced into a fluid of different density behaves exactly like a unicellular organism.

From Morals and the Evolution of Man by Nordau, Max Simon

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