The Collaborative International Dictionary of English v.0.48:

Muffle \Muf"fle\, v. i. [Cf. F. maffle, mumble, D. moffelen.]
   To speak indistinctly, or without clear articulation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Muffle \Muf"fle\, n. [F. moufle, prop., a mitten, from the
   resemblance in shape. See Muffle, v. t., Muff.]
   1. Anything with which another thing, as an oar or drum, is
      muffled; also, a boxing glove; a muff.
      [1913 Webster]

   2. (Metal.) An earthenware compartment or oven, often shaped
      like a half cylinder, used in furnaces to protect objects
      heated from the direct action of the fire, as in
      scorification of ores, cupellation of ore buttons, etc.
      [1913 Webster]

   3. (Ceramics) A small oven for baking and fixing the colors
      of painted or printed pottery, without exposing the
      pottery to the flames of the furnace or kiln.
      [1913 Webster]

   4. A pulley block containing several sheaves. --Knight.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Muffle \Muf"fle\ (m[u^]f"f'l), n.
   The bare end of the nose between the nostrils; -- used esp.
   of ruminants.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Muffle \Muf"fle\, v. t. [imp. & p. p. Muffled; p. pr. & vb. n.
   Muffling.] [Cf. F. moufle a mitten, LL. muffula, OD. moffel
   a muff. See Muff.]
   1. To wrap up in something that conceals or protects; to
      wrap, as the face and neck, in thick and disguising folds;
      hence, to conceal or cover the face of; to envelop; to
      inclose; -- often with up. --South.
      [1913 Webster]

            The face lies muffled up within the garment.
                                                  --Addison.
      [1913 Webster]

            He muffled with a cloud his mournful eyes. --Dryden.
      [1913 Webster]

            Muffled up in darkness and superstition.
                                                  --Arbuthnot.
      [1913 Webster]

   2. To prevent seeing, or hearing, or speaking, by wraps bound
      about the head; to blindfold; to deafen.
      [1913 Webster]

   3. To wrap or fit with something that dulls or deadens the
      sound of; as, to muffle the strings of a drum, or that
      part of an oar which rests in the rowlock; to muffle the
      exhaust of a motor vehicle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

muffle
    n 1: a kiln with an inner chamber for firing things at a low
         temperature
    v 1: conceal or hide; "smother a yawn"; "muffle one's anger";
         "strangle a yawn" [syn: smother, stifle, strangle,
         muffle, repress]
    2: deaden (a sound or noise), especially by wrapping [syn:
       muffle, mute, dull, damp, dampen, tone down]

Moby Thesaurus II by Grady Ward, 1.0:

128 Moby Thesaurus words for "muffle":
   acoustic tile, antiknock, antlia, apply to, baffle, baffler, beak,
   beezer, bill, black out, blanket, block, bugle, bundle up, canopy,
   censor, choke, choke off, cloak, clothe, cloud, conceal, conk,
   cope, cover, cover up, cowl, curtain, cushion, damp, dampen,
   dampener, damper, deaden, deafen, dull, dumbfound, eclipse, enfold,
   enshroud, envelop, film, gag, hap, hood, hugger-mugger, hush,
   hush up, hush-hush, hushcloth, kill, lay on, lay over, mantle,
   mask, mellow, muffle up, muffler, mute, muzzle, nares, neb, nib,
   nose, nostrils, nozzle, obduce, obscure, occult, olfactory organ,
   overlay, overspread, pecker, proboscis, protect, put on,
   put to silence, quash, quiet, quieten, quietener, repress,
   rhinarium, rostrum, schnozzle, screen, scum, shield, shroud, shush,
   shut down on, silence, silence cloth, silencer, sit on, smeller,
   smother, snoot, snout, soft pedal, soft-pedal, soften, sordine,
   sordino, sound-absorbing material, soundproofing,
   soundproofing insulation, sourdine, spread over, squash, squelch,
   stifle, still, stop, strangle, strike dumb, subdue, superimpose,
   superpose, suppress, swaddle, swathe, throttle, tone down, trunk,
   veil, wrap, wrap up