ro·​ti·​fer ˈrō-tə-fər How to pronounce rotifer (audio)
: any of a class (Rotifera of the phylum Aschelminthes) of minute usually microscopic but many-celled chiefly freshwater aquatic invertebrates having the anterior end modified into a retractile disk bearing circles of strong cilia that often give the appearance of rapidly revolving wheels

Example Sentences

Recent Examples on the Web Meet the rotifer:The microscopic animal that came back to life after 24,000 years frozen The Paraceratherium linxiaense had a body weight of 24 tons, similar to the total weight of four large African elephants or eight white rhinos, according to Deng. Sudiksha Kochi, USA TODAY, 17 June 2021 The tiny creature is called a bdelloid rotifer. Mike Wehner, BGR, 8 June 2021 The creatures were a type of rotifer, some of the toughest animals on the planet. Matthew Twombly, National Geographic, 8 Dec. 2021 Genomic evidence for ameiotic evolution in the bdelloid rotifer Adineta vaga. Razib Khan, Discover Magazine, 22 July 2013 Once eaten, the fungal spores produce cells that threaten to devour the rotifer from the inside out within just 2 weeks. Ed Yong, Discover Magazine, 29 Jan. 2010 Radiocarbon dating revealed the rotifer to be twenty-four thousand years old. Joshua Yaffa, The New Yorker, 10 Jan. 2022 But even that near-suspension of animation would have nothing on a rotifer: one of these microscopic animals, pulled out of Siberian permafrost, spent the past 25,000 years in a frozen nap before being reanimated. Andrea Thompson, Scientific American, 27 Dec. 2021 A month later, a microscopic, wormlike invertebrate known as a bdelloid rotifer was crawling around inside. Joshua Yaffa, The New Yorker, 10 Jan. 2022 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'rotifer.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


ultimately from Latin rota + -fer

First Known Use

1777, in the meaning defined above

Time Traveler
The first known use of rotifer was in 1777

Dictionary Entries Near rotifer

Cite this Entry

“Rotifer.” Dictionary, Merriam-Webster, Accessed 31 May. 2023.

Kids Definition


ro·​ti·​fer ˈrōt-ə-fər How to pronounce rotifer (audio)
: any of a class of tiny aquatic invertebrate animals with circles of cilia on one end that look like moving wheels when moving

Medical Definition


ro·​ti·​fer ˈrōt-ə-fər How to pronounce rotifer (audio)
: any member of the class Rotifera

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