Nematoda

noun plural

Nem·​a·​to·​da ˌnem-ə-ˈtō-də 

: a phylum related to the Aschelminthes and comprising elongated cylindrical worms without an epithelial coelomic lining, with dorsal and ventral nerve cords, and with lateral excretory ducts that are parasites of humans, animals, or plants or free-living dwellers in soil or water and are known as roundworms, eelworms, or nematodes