tapeworm /ˈteɪpˌwɝm/noun 3verb 2forms 3 noun3 •Any parasitical worm of the class or infraclass Cestoda, which infests the intestines of animals, including humans, often infecting different host species during their life cycle. •A broad fish tapeworm, Diphyllobothrium latum. •Infection by tapeworms.We used to have a lot of tapeworm down in my neck of the woods, but we don't have much now. — 1967 verb2 •To treat (an animal) for tapeworm infection. •To move along in a wriggling manner, like a tapeworm. formstapewormed · tapeworming · tapeworms