Definitions of dead nettle:

noun: any of various plants of the genus Lamium having clusters of small usually purplish flowers with two lips
noun: coarse bristly Eurasian plant with white or reddish flowers and foliage resembling that of a nettle; common as a weed in United States
noun: foul-smelling perennial Eurasiatic herb with a green creeping rhizome
noun: a plants of the genus Pilea having drooping green flower clusters and smooth translucent stems and leaves