noun 1.the dried, unexpanded flower heads of a wormwood, Artemisia cina (Levant wormseed) or the fruit of certain goosefoots, especially Chenopodium anthelminticum (or C. ambrosioides ), the Mexican tea or American wormseed, used as an anthelmintic drug.
Origin: 1350–1400; Middle English wyrmsed. See
worm,
seed