The Collaborative International Dictionary of English v.0.48:

Snoring \Snor"ing\, n. (Physiol.)
   The act of respiring through the open mouth so that the
   currents of inspired and expired air cause a vibration of the
   uvula and soft palate, thus giving rise to a sound more or
   less harsh. It is usually unvoluntary, but may be produced
   voluntarily.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Snore \Snore\ (sn[=o]r), v. i. [imp. & p. p. Snored
   (sn[=o]rd); p. pr. & vb. n. Snoring.] [OE. snoren, AS.
   snora a snoring; akin to LG. snoren, snorken, snurken, to
   snore, D. snorken, G. schnarchen to snore, schnarren to
   rattle, MHG. snarren, Sw. snarka to snore, Icel. snarka to
   sputter, fizzle. Cf. Snarl to growl, Sneer, Snort. See
   Snoring.]
   To breathe with a rough, hoarse, nasal voice in sleep.
   [1913 Webster]

WordNet (r) 3.0 (2006):

snoring
    n 1: the act of snoring or producing a snoring sound [syn:
         snore, snoring, stertor]

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "snoring":
   Aqua-Lung, artificial respiration, aspiration, asthmatic,
   asthmatic wheeze, breath, breath of air, breathing, broken wind,
   cough, effervescent, errhine, exhalation, expiration, expiratory,
   exsufflation, fizzling, gasp, gulp, hack, heaving, hiccup, hissing,
   huffing, hushing, inhalation, inhalator, inspiration, inspiratory,
   insufflation, iron lung, mouth-to-mouth resuscitation, nasal,
   oxygen mask, oxygen tent, pant, panting, pneumonic, puff, puffing,
   pulmonary, pulmonic, respiration, respiratory, rhinal, scuba,
   sibilant, sigh, sissing, sizzling, sneeze, sneezy, sniff, sniffing,
   sniffle, sniffling, sniffly, sniffy, snore, snorting, snuff,
   snuffle, snuffling, snuffly, snuffy, sternutation, sternutatory,
   stertor, stertorous, suspiration, wheeze, wheezing, wheezy, wind