a European plant, Leonorus cardiaca, of the mint family, an introduced weed in the U.S., having cut leaves with a whorl of lavender flowers in the axils.
Origin: 1350–1400; ME moderwort (see mother1, wort2), so called because believed helpful for diseases of the womb
moth·er·wort (mŭth'ər-wûrt', -wôrt') n. Any of several Eurasian plants of the genus Leonurus, especially L. cardiaca, a weed having clusters of small purple or pink flowers and spine-tipped calyx lobes.
[Middle English moderwort : moder, mother, womb (from its use in treating diseases of the uterus); see mother1 + wort, wort; see wort1.]