roundworm

noun

round·​worm ˈrau̇nd-ˌwərm 

: nematode

also : a related round-bodied unsegmented worm (such as a spiny-headed worm) as distinguished from a flatworm

Examples of roundworm in a Sentence

Recent Examples on the Web

This microscopic roundworm lays its eggs in root tissues, causing swellings or galls to develop on infected roots. —Kim Toscano, Southern Living, 9 July 2025

According to the complaint, the biological material Han is accused of smuggling — sometimes hidden between pages of a book — is related to roundworms and requires a government permit. —Jennifer Jett, NBC news, 10 June 2025

Scientists have captured the first videos of wild roundworms forming living, wriggling towers that behave as one big superorganism By Jacek Krywko edited by Allison Parshall Join Our Community of Science Lovers! —Jacek Krywko, Scientific American, 5 June 2025

When food runs out, certain tiny roundworms, barely visible to the naked eye, crawl toward one another and build living, wriggling towers that move as one superorganism. —Jacek Krywko, Scientific American, 5 June 2025

Word History

First Known Use

1558, in the meaning defined above

Kids Definition

roundworm

noun

round·​worm ˈrau̇n-ˌdwərm 

: a nematode worm (as a hookworm)

also : a related round-bodied worm without segments as compared to a flatworm

Medical Definition

roundworm

noun

round·​worm ˈrau̇n-ˌdwərm 

: nematode

also : a related round-bodied unsegmented worm (as an acanthocephalan) as distinguished from a flatworm