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

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

Humble roundworms put cheerleaders’ pyramid-building skills to shame. —Lauren Leffer, Popular Science, 5 June 2025

Indeed, while many species’ reactions to death are mediated mainly by sight, that certainly wasn’t the case for wiggling roundworms, which have no eyes and no sense of vision. —Sam Walters, Discover Magazine, 23 May 2025

This nauseating roundworm is a known plague in Hawaii. —Ars Technica, 13 Feb. 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