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.
      [1913 Webster]

            Thou shalt not muzzle the ox when he treadeth out
            the corn.                             --Deut. xxv.
                                                  4.
      [1913 Webster]

   2. To fondle with the closed mouth. [Obs.] --L'Estrange.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Muzzle \Muz"zle\, v. i.
   To bring the mouth or muzzle near.
   [1913 Webster]

         The bear muzzles and smells to him.      --L'Estrange.
   [1913 Webster]

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.
      [1913 Webster]

   2. The mouth of a thing; the end for entrance or discharge;
      as, the muzzle of a gun.
      [1913 Webster]

   3. A fastening or covering (as a band or cage) for the mouth
      of an animal, to prevent eating or vicious biting.
      [1913 Webster]

            With golden muzzles all their mouths were bound
                                                  --Dryden.
      [1913 Webster]

   Muzzle sight. (Gun.) See Dispart, n., 2.
      [1913 Webster]

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]

Moby Thesaurus II by Grady Ward, 1.0:

168 Moby Thesaurus words for "muzzle":
   Oregon boat, acoustic tile, antiknock, antlia, asphyxiate, baffler,
   bazoo, beak, beezer, bilbo, bill, bond, bonds, bottle up, bridle,
   bugle, camisole, censor, chains, chaps, choke, choke off, chops,
   clamp down on, collar, conk, cork, cork up, countenance,
   crack down on, crush, cuffs, cushion, damp, damp down, dampener,
   damper, deflate, dial, disarm, drown, dumbfound, embouchure,
   enchain, extinguish, face, features, fetter, gab, gag, gob, gyves,
   halter, hamper, hamstring, handcuff, handcuffs, hobble, hobbles,
   hog-tie, hold down, hopples, hush, hush-hush, hushcloth, irons,
   jaw, jaws, jowls, jump on, keep down, keep under, kill, kisser,
   knock out, leading strings, leash, lips, manacle, mandibles, map,
   maw, maxilla, mouth, muffle, muffler, mug, mush, mute, nares, neb,
   nib, nose, nostrils, nozzle, olfactory organ, oral cavity,
   paralyze, pecker, phiz, pillory, pour water on, premaxilla,
   proboscis, prostrate, puss, put down, put to silence, quash, quell,
   quench, quiet, quieten, quietener, reins, repress, restraint,
   restraints, rhinarium, rostrum, schnozzle, shackle, shush,
   shut down on, silence, silence cloth, silencer, sit down on,
   sit on, smash, smeller, smother, snoot, snout, soft pedal,
   soft-pedal, sordine, sordino, sound-absorbing material,
   soundproofing, soundproofing insulation, sourdine, squash, squelch,
   stanch, stifle, still, stocks, straightjacket, strait-waistcoat,
   straitjacket, strangle, stranglehold, strike dumb, stultify,
   subdue, suffocate, suppress, tether, throttle, trammel, trammels,
   trap, trunk, truss up, visage, yap, yoke



Easton's 1897 Bible Dictionary:

Muzzle
   Grain in the East is usually thrashed by the sheaves being
   spread out on a floor, over which oxen and cattle are driven to
   and fro, till the grain is trodden out. Moses ordained that the
   ox was not to be muzzled while thrashing. It was to be allowed
   to eat both the grain and the straw (Deut. 25:4). (See AGRICULTURE.)