The Collaborative International Dictionary of English v.0.48:

Quench \Quench\, v. t. [imp. & p. p. Quenched; p. pr. & vb. n.
   Quenching.] [OE. quenchen, AS. cwencan in [=a]cwencan, to
   extinguish utterly, causative of cwincan, [=a]cwincan, to
   decrease, disappear; cf. AS. cw[imac]nan, [=a]cw[imac]nan, to
   waste or dwindle away.]
   1. To extinguish; to overwhelm; to make an end of; -- said of
      flame and fire, of things burning, and figuratively of
      sensations and emotions; as, to quench flame; to quench a
      candle; to quench thirst, love, hate, etc.
      [1913 Webster]

            Ere our blood shall quench that fire. --Shak.
      [1913 Webster]

            The supposition of the lady's death
            Will quench the wonder of her infamy. --Shak.
      [1913 Webster]

   2. To cool suddenly, as heated steel, in tempering.
      [1913 Webster]

   Syn: To extinguish; still; stifle; allay; cool; check.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quench \Quench\, v. i.
   To become extinguished; to go out; to become calm or cool.
   [R.]
   [1913 Webster]

         Dost thou think in time
         She will not quench!                     --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

quench
    v 1: satisfy (thirst); "The cold water quenched his thirst"
         [syn: quench, slake, allay, assuage]
    2: put out, as of fires, flames, or lights; "Too big to be
       extinguished at once, the forest fires at best could be
       contained"; "quench the flames"; "snuff out the candles"
       [syn: snuff out, blow out, extinguish, quench] [ant:
       ignite, light]
    3: electronics: suppress (sparking) when the current is cut off
       in an inductive circuit, or suppress (an oscillation or
       discharge) in a component or device
    4: suppress or crush completely; "squelch any sign of dissent";
       "quench a rebellion" [syn: squelch, quell, quench]
    5: reduce the degree of (luminescence or phosphorescence) in
       (excited molecules or a material) by adding a suitable
       substance
    6: cool (hot metal) by plunging into cold water or other liquid;
       "quench steel"

Moby Thesaurus II by Grady Ward, 1.0:

88 Moby Thesaurus words for "quench":
   allay, appease, asphyxiate, assuage, blow out, blunt, bottle up,
   censor, chill, choke, choke off, clamp down on, cool, cork,
   cork up, crack down on, crush, damp, damp down, dampen, deflect,
   destroy, deter, disaffect, discourage, disincline, disinterest,
   distract, divert, douse, drown, extinguish, feast, feed, gag,
   gratify, hold down, indispose, jump on, keep down, keep under,
   kill, muzzle, out, overcome, pour water on, put, put down, put off,
   put out, quash, quell, reduce, regale, repel, repress, sate,
   satiate, satisfy, shut down on, silence, sit down on, sit on,
   slack, slake, smash, smother, snuff, snuff out, squash, squelch,
   stamp out, stanch, stifle, strangle, stultify, subdue, suffocate,
   suppress, surfeit, throttle, trample out, trample underfoot,
   turn aside, turn away, turn from, turn off, wean from