The Collaborative International Dictionary of English v.0.48:

Snuffle \Snuf"fle\, v. i. [imp. & p. p. Snuffled; p. pr. & vb.
   n. Snuffling.] [Freq. of snuff, v.i.; akin to LG. snuffeln,
   G. schn["u]ffeln, D. snuffeln, Dan. sn["o]vle. Cf.
   Sniffle.]
   To speak through the nose; to breathe through the nose when
   it is obstructed, so as to make a broken sound.
   [1913 Webster]

         One clad in purple
         Eats, and recites some lamentable rhyme . . .
         Snuffling at nose, and croaking in his throat.
                                                  --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Snuffle \Snuf"fle\, n.
   1. The act of snuffing; a sound made by the air passing
      through the nose when obstructed.
      [1913 Webster]

            This dread sovereign, Breath, in its passage, gave a
            snort or snuffle.                     --Coleridge.
      [1913 Webster]

   2. An affected nasal twang; hence, cant; hypocrisy.
      [1913 Webster]

   3. pl. Obstruction of the nose by mucus; nasal catarrh of
      infants or children. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

snuffle
    n 1: the act of breathing heavily through the nose (as when the
         nose is congested) [syn: snuffle, sniffle, snivel]
    v 1: sniff or smell inquiringly [syn: snuff, snuffle]
    2: snuff up mucus through the nose [syn: snuffle, snivel]
    3: cry or whine with snuffling; "Stop snivelling--you got
       yourself into this mess!" [syn: snivel, sniffle,
       blubber, blub, snuffle]

Moby Thesaurus II by Grady Ward, 1.0:

150 Moby Thesaurus words for "snuffle":
   Aqua-Lung, Tartuffery, Tartuffism, affectation,
   artificial respiration, aspirate, aspiration, assibilate,
   assibilation, asthmatic wheeze, be hypocritical, blandish, blow,
   breath, breath of air, breathe, breathe hard, breathe in,
   breathe out, breathing, broken wind, buzz, cant, cough, draw in,
   effervesce, effervescence, effervescing, exhalation, exhale,
   exhaust, expel, expiration, expire, exsufflation, false piety,
   falseness, fizz, fizzle, fizzling, frication, frictional rustling,
   gasp, give lip service, give mouth honor, goody-goodiness, gulp,
   hack, hiccup, hiss, hissing, huff, hush, hushing, hypocrisy,
   inhalation, inhalator, inhale, inhalement, insincerity,
   inspiration, inspire, insufflation, iron lung, lisp,
   mealymouthedness, mouth, mouth-to-mouth resuscitation, mummery,
   nose, oiliness, oxygen mask, oxygen tent, pant, pharisaicalness,
   pharisaism, pietism, pietisticalness, piety, piousness,
   play the hypocrite, puff, reek of piety, religionism, religiosity,
   render lip service, respiration, respire, rhonchus,
   sanctimoniousness, sanctimony, scent, scuba, self-righteousness,
   shush, shushing, sibilance, sibilate, sibilation, siffle, sigh,
   sigmatism, siss, sissing, sizz, sizzle, sizzling, slurp, smell,
   smell of, sneeze, sneezing, sniff, sniffle, snivel, snore, snoring,
   snort, snuff, snuff in, soft-soap, spit, splutter, sputter, squash,
   squelch, squish, sternutation, stertor, suck, suck in, sucking,
   suckle, suction, suspiration, sweet-talk, swish, twang, unction,
   unctuousness, wheeze, whiff, whish, whistle, whistling,
   white noise, whiz, whoosh, wind, zip