The Collaborative International Dictionary of English v.0.48:

Mute \Mute\, a. [L. mutus; cf. Gr. my`ein to shut, Skr. m[=u]ta
   bound, m[=u]ka dumb: cf. OE. muet, fr. F. muet, a dim. of OF.
   mu, L. mutus.]
   1. Not speaking; uttering no sound; silent.
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            All the heavenly choir stood mute,
            And silence was in heaven.            --Milton.
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   Note: In law a prisoner is said to stand mute, when, upon
         being arranged, he makes no answer, or does not plead
         directly, or will not put himself on trial.
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   2. Incapable of speaking; dumb. --Dryden.
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   3. Not uttered; unpronounced; silent; also, produced by
      complete closure of the mouth organs which interrupt the
      passage of breath; -- said of certain letters. See 5th
      Mute, 2.
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   4. Not giving a ringing sound when struck; -- said of a
      metal.
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   Mute swan (Zool.), a European wild white swan (Cygnus
      olor syn. Cygnus gibbus), which produces no loud notes,
      in distinction from the Trumpeter swan.
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   Syn: Silent; dumb; speechless.

   Usage: Mute, Silent, Dumb. One is silent who does not
          speak; one is dumb who can not, for want of the proper
          organs; as, a dumb beast, etc.; and hence,
          figuratively, we speak of a person as struck dumb with
          astonishment, etc. One is mute who is held back from
          speaking by some special cause; as, he was mute
          through fear; mute astonishment, etc. Such is the case
          with most of those who never speak from childhood;
          they are not ordinarily dumb, but mute because they
          are deaf, and therefore never learn to talk; and hence
          their more appropriate name is deaf-mutes.
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                They spake not a word;
                But, like dumb statues, or breathing stones,
                Gazed each on other.              --Shak.
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                All sat mute,
                Pondering the danger with deep thoughts.
                                                  --Milton.
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WordNet (r) 3.0 (2006):

mute swan
    n 1: soundless Eurasian swan; commonly domesticated [syn: mute
         swan, Cygnus olor]