The Collaborative International Dictionary of English v.0.48:

Quell \Quell\, v. t. [OE. quellen to kill, AS. cwellan,
   causative of cwelan to die; akin to OHG. quellen to torment,
   Icel. kvelja. See Quail to cower.]
   1. To take the life of; to kill. [Obs.] --Spenser.
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            The ducks cried as [if] men would them quelle.
                                                  --Chaucer.
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   2. To overpower; to subdue; to put down.
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            The nation obeyed the call, rallied round the
            sovereign, and enabled him to quell the disaffected
            minority.                             --Macaulay.
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            Northward marching to quell the sudden revolt.
                                                  --Longfellow.
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   3. To quiet; to allay; to pacify; to cause to yield or cease;
      as, to quell grief; to quell the tumult of the soul.
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            Much did his words the gentle lady quell. --Spenser.
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   Syn: to subdue; crush; overpower; reduce; put down; repress;
        suppress; quiet; allay; calm; pacify.
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The Collaborative International Dictionary of English v.0.48:

Quell \Quell\, n.
   Murder. [Obs.] --Shak.
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The Collaborative International Dictionary of English v.0.48:

Quell \Quell\, v. i. [imp. & p. p. Quelled; p. pr. & vb. n.
   Quelling.] [See Quail to cower.]
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   1. To die. [Obs.]
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            Yet he did quake and quaver, like to quell.
                                                  --Spenser.
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   2. To be subdued or abated; to yield; to abate. [R.]
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            Winter's wrath begins to quell.       --Spenser.
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WordNet (r) 3.0 (2006):

quell
    v 1: suppress or crush completely; "squelch any sign of
         dissent"; "quench a rebellion" [syn: squelch, quell,
         quench]
    2: overcome or allay; "quell my hunger" [syn: quell, stay,
       appease]

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "quell":
   allay, alleviate, annihilate, appease, asphyxiate, assuage,
   beat down, bend, bottle up, break, break down, bring low,
   bring to terms, calm, calm down, censor, choke, choke off,
   clamp down on, compose, conquer, cool, cork, cork up,
   crack down on, cradle, crush, damp down, drown, dulcify, ease,
   even out, extinguish, fell, flatten, gag, gentle, hold down,
   humble, humiliate, hush, jump on, keep down, keep under, kill,
   lull, master, mitigate, moderate, mollify, muzzle, overcome,
   overmaster, override, overwhelm, pacify, pour balm into,
   pour water on, prostrate, put down, put out, quash, quench, quiet,
   reduce, repress, rest, ride down, rock, rock to sleep,
   shut down on, silence, sit down on, sit on, smash, smooth,
   smooth down, smooth over, smoothen, smother, snuff out, soothe,
   squash, squelch, stabilize, stamp out, stanch, steady, stifle,
   still, strangle, stultify, subdue, subjugate, suffocate, suppress,
   throttle, trample down, trample out, trample underfoot,
   tranquilize, tread underfoot, tyrannize, unman, vanquish