flatworm

noun

flat·worm ˈflat-ˌwərm

: 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

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

The flatworm doesn’t feed on or live within your pet. — Hanna Wickes, Charlotte Observer, 9 Apr. 2026 Ruptures, tears, and cracks are known to shape zebra fish nostrils, hydra mouths, fruit fly legs, and whole flatworms. — Clare Watson, Quanta Magazine, 27 Feb. 2026 These flatworms aren’t parasites. — Hanna Wickes, Miami Herald, 9 Apr. 2026 And the flatworm with its new noggin immediately solving the maze its old one worked so diligently to master? — Christian Wiman, Harpers Magazine, 30 Dec. 2025 See All Example Sentences for flatworm

Word History

First Known Use

1874, in the meaning defined above

Time Traveler

The first known use of flatworm was in 1874

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Style

“Flatworm.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/flatworm. Accessed 7 Jul. 2026.

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Kids Definition

flatworm

noun

flat·worm -ˌwərm

: any of a phylum of simple worms (as planarians, flukes, or tapeworms) that have a soft flat body, lack a body cavity, and have bilateral symmetry

Medical Definition

flatworm

noun

flat·worm ˈflat-ˌwərm

: any worm of the phylum Platyhelminthes : platyhelminth

especially : turbellarian

flatworm

noun

Examples of flatworm in a Sentence

Word History

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Medical Definition

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