flat·​worm | \ ˈflat-ˌwərm How to pronounce flatworm (audio) \

Definition of flatworm

: any of a phylum (Platyhelminthes) of soft-bodied usually much flattened acoelomate worms (such as the planarians, flukes, and tapeworms)

called also platyhelminth

Examples of flatworm in a Sentence

Recent Examples on the Web While wormwood has been researched5 for its possible antiparasitic effects in animals, a recent study6 looking at its efficacy in treating a type of flatworm infection in humans was later retracted. Casey Gueren, SELF, 19 Aug. 2021 In the sixty years since Samuel first published his seminal machine learning work, artificial intelligence has advanced from being not as smart as a flatworm to having less common sense than a house cat. Gil Press, Forbes, 28 May 2021 Some of the most important discoveries of his career hinge on the planarian—a type of flatworm about two centimetres long that, under a microscope, resembles a cartoon of a cross-eyed phallus. Matthew Hutson, The New Yorker, 3 May 2021 Our common ancestor with them is thought to be a flatworm with only the most rudimentary of nervous systems; octopus brains are essentially a separate evolutionary experiment in developing intelligence. Philip Ball, The New Yorker, 27 Apr. 2021 Mating can be competitive, with a single flatworm fertilizing another. Corryn Wetzel, Smithsonian Magazine, 17 Nov. 2020 Some species of flatworm engage in this duel to see who can inseminate the other. Corryn Wetzel, Smithsonian Magazine, 17 Nov. 2020 Plants, roundworms, flatworms and insects use RNA to carry signals through their tissues, and perhaps further. Quanta Magazine, 8 Nov. 2013 In nature, the organisms that exhibit it are thought to be in other groups only, like flatworms. Caroline Delbert, Popular Mechanics, 30 Dec. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'flatworm.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of flatworm

1874, in the meaning defined above

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The first known use of flatworm was in 1874

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Dictionary Entries Near flatworm

flatwork ironer


flat wrack

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Last Updated

29 Aug 2021

Cite this Entry

“Flatworm.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/flatworm. Accessed 23 Sep. 2021.

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More Definitions for flatworm


flat·​worm | \ ˈflat-ˌwərm How to pronounce flatworm (audio) \

Medical Definition of flatworm

: any worm of the phylum Platyhelminthes : platyhelminth especially : turbellarian

More from Merriam-Webster on flatworm

Britannica.com: Encyclopedia article about flatworm


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