The Collaborative International Dictionary of English v.0.48:

Muzzle \Muz"zle\, v. t. [imp. & p. p. Muzzled; p. pr. & vb. n.
   Muzzling.] [F. museler.]
   1. To bind the mouth of; to fasten the mouth of, so as to
      prevent biting or eating; hence, figuratively, to bind; to
      sheathe; to restrain from speech or action; as, the
      dictator muzzled all the newspapers. "My dagger muzzled."
      --Shak.
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            Thou shalt not muzzle the ox when he treadeth out
            the corn.                             --Deut. xxv.
                                                  4.
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   2. To fondle with the closed mouth. [Obs.] --L'Estrange.
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The Collaborative International Dictionary of English v.0.48:

Muzzle \Muz"zle\, v. i.
   To bring the mouth or muzzle near.
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         The bear muzzles and smells to him.      --L'Estrange.
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The Collaborative International Dictionary of English v.0.48:

Muzzle \Muz"zle\, n. [OE. mosel, OF. musel, F. museau muzzle or
   snout, LL. musellus, fr. musus, morsus. See Muse, v. i.,
   and cf. Morsel.]
   1. The projecting mouth and nose of a quadruped, as of a
      horse; a snout.
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   2. The mouth of a thing; the end for entrance or discharge;
      as, the muzzle of a gun.
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   3. A fastening or covering (as a band or cage) for the mouth
      of an animal, to prevent eating or vicious biting.
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            With golden muzzles all their mouths were bound
                                                  --Dryden.
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   Muzzle sight. (Gun.) See Dispart, n., 2.
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WordNet (r) 3.0 (2006):

muzzle
    n 1: the open circular discharging end of a gun [syn: gun
         muzzle, muzzle]
    2: forward projecting part of the head of certain animals;
       includes the jaws and nose
    3: a leather or wire restraint that fits over an animal's snout
       (especially a dog's nose and jaws) and prevents it from
       eating or biting
    4: restraint put into a person's mouth to prevent speaking or
       shouting [syn: gag, muzzle]
    v 1: fit with a muzzle; "muzzle the dog to prevent it from
         biting strangers" [ant: unmuzzle]
    2: prevent from speaking out; "The press was gagged" [syn:
       gag, muzzle]
    3: tie a gag around someone's mouth in order to silence them;
       "The burglars gagged the home owner and tied him to a chair"
       [syn: gag, muzzle]