Source : Webster's Revised Unabridged Dictionary (1913)

Mugwort \Mug"wort`\, n. [AS. mucgwyrt. Cf. {Midge}.] (Bot.)
   A somewhat aromatic composite weed ({Artemisia vulgaris}), at
   one time used medicinally; -- called also {motherwort}.

Source : WordNet®

mugwort
     n : any of several weedy composite plants of the genus Artemisia