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

Severing a flatworm usually just results in two identical flatworms, but something appears to have gone awry in one individual, who returned with another head where his tail should have been. —Nathaniel Scharping, Discover Magazine, 13 June 2017

More emojis of plants, mollusks, flatworms, fungi and microorganisms could help spark new conversations about conservation and biodiversity, a new study argues. —Corinne Purtill, Los Angeles Times, 12 Dec. 2023

This giant invasive flatworm, a Diversibipalium 'blue,' made its way to a French territory off Africa. —Lauren Sigfusson, Discover Magazine, 22 May 2018

Planarian and the Stem Cell Method Take the flatworm, for example, also known as Planarian and one of the most impressive examples of regeneration in the animal kingdom. —Sofia Quaglia, Discover Magazine, 6 Feb. 2023

That’s because another predator has moved in: New Guinea flatworms. —Sarah Kuta, Smithsonian Magazine, 2 May 2023

This flatworm has truly astonishing powers of regeneration. —Seriously Science, Discover Magazine, 15 July 2013

And instead of conducting an underwater band, Sebastian (played by Daveed Diggs) now kicks off a massive dance party, complete with toe-tapping sea turtles, spinning mimic octopuses, waving flatworms and ascending luminescent jellyfish. —Ashley Lee, Los Angeles Times, 26 May 2023

At a school biology club meeting, Polyak cut up flatworms called planaria and watched their heads and tails regenerate. —Adithi Ramakrishnan, Dallas News, 17 May 2023

Word History

First Known Use

1874, in the meaning defined above

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