Source : Webster's Revised Unabridged Dictionary (1913)

Mussel \Mus"sel\, n. [See {Muscle}, 3.]
   1. (Zo["o]l.) Any one of many species of marine bivalve
      shells of the genus {Mytilus}, and related genera, of the
      family {Mytid[ae]}. The common mussel ({Mytilus edulis};
      see Illust. under {Byssus}), and the larger, or horse,
      mussel ({Modiola modiolus}), inhabiting the shores both of
      Europe and America, are edible. The former is extensively
      used as food in Europe.

   2. (Zo["o]l.) Any one of numerous species of {Unio}, and
      related fresh-water genera; -- called also {river mussel}.
      See {Naiad}, and {Unio}.

   {Mussel digger} (Zo["o]l.), the grayback whale. See {Gray
      whale}, under {Gray}.