The Collaborative International Dictionary of English v.0.48:

Archangel \Arch`an"gel\, n. [L. archangelus, Gr. 'archa`ggelos:
   cf. OF. archangel, F. archange. See Arch-, pref., and
   Angel.]
   1. A chief angel; one high in the celestial hierarchy.
      --Milton.
      [1913 Webster]

   2. (Bot.) A term applied to several different species of
      plants (Angelica archangelica, Lamium album, etc.).
      [1913 Webster]

WordNet (r) 3.0 (2006):

Lamium album
    n 1: European dead nettle with white flowers [syn: white dead
         nettle, Lamium album]