Wormseed \Worm"seed`\, n. (Bot.) Any one of several plants, as {Artemisia santonica}, and {Chenopodium anthelminticum}, whose seeds have the property of expelling worms from the stomach and intestines. [1913 Webster] {Wormseed mustard}, a slender, cruciferous plant ({Erysinum cheiranthoides}) having small lanceolate leaves. [1913 Webster]