wormseed Syllabification: (worm·seed)Pronunciation: /ˈwərmˌsēd/Definition of wormseed noun a plant whose seeds have anthelmintic properties. (also Levant wormseed) santonica. (also American wormseed) an American plant of the goosefoot family (Chenopodium ambrosioides, family Chenopodiaceae). wormseed in other Oxford dictionaries Definition of wormseed in the British & World English dictionary