The Collaborative International Dictionary of English v.0.48:

Allay \Al*lay"\, v. t.
   To diminish in strength; to abate; to subside. "When the rage
   allays." --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Allay \Al*lay"\, n.
   Alleviation; abatement; check. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Allay \Al*lay"\, n.
   Alloy. [Obs.] --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Allay \Al*lay"\, v. t.
   To mix (metals); to mix with a baser metal; to alloy; to
   deteriorate. [Archaic] --Fuller.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Allay \Al*lay"\, v. t. [imp. & p. p. Allayed; p. pr. & vb. n.
   Allaying.] [OE. alaien, aleggen, to lay down, put down,
   humble, put an end to, AS. [=a]lecgan; [=a]- (cf. Goth. us-,
   G. er-, orig. meaning out) + lecgan to lay; but confused with
   old forms of allege, alloy, alegge. See Lay.]
   1. To make quiet or put at rest; to pacify or appease; to
      quell; to calm; as, to allay popular excitement; to allay
      the tumult of the passions.
      [1913 Webster]

   2. To alleviate; to abate; to mitigate; as, to allay the
      severity of affliction or the bitterness of adversity.
      [1913 Webster]

            It would allay the burning quality of that fell
            poison.                               --Shak.
      [1913 Webster]

   Syn: To alleviate; check; repress; assuage; appease; abate;
        subdue; destroy; compose; soothe; calm; quiet. See
        Alleviate.
        [1913 Webster]

WordNet (r) 3.0 (2006):

allay
    v 1: lessen the intensity of or calm; "The news eased my
         conscience"; "still the fears" [syn: still, allay,
         relieve, ease]
    2: satisfy (thirst); "The cold water quenched his thirst" [syn:
       quench, slake, allay, assuage]

Moby Thesaurus II by Grady Ward, 1.0:

120 Moby Thesaurus words for "allay":
   abate, alleviate, anesthetize, appease, assuage, attemper, balm,
   bank the fire, benumb, blunt, calm, chasten, cloy, compose,
   conciliate, constrain, control, cool, cram, cushion, damp, dampen,
   de-emphasize, deaden, deaden the pain, defuse, deliver, diminish,
   disburden, disembarrass, disencumber, downplay, dulcify, dull,
   ease, ease matters, engorge, extenuate, feast, feed, fill, fill up,
   foment, free, give relief, glut, gorge, gratify, jade,
   keep within bounds, lay, lay the dust, lenify, lessen, lighten,
   lull, mitigate, moderate, modulate, mollify, numb, obtund,
   overdose, overfeed, overfill, overgorge, oversaturate, overstuff,
   pacify, pad, pall, palliate, placate, play down, poultice,
   pour balm into, pour balm on, pour oil on, propitiate, quench,
   quiet, quieten, reduce, reduce the temperature, regale, release,
   relieve, restrain, salve, sate, satiate, satisfy, saturate, settle,
   slacken, slake, slow down, smooth, smooth down, smooth over,
   smother, sober, sober down, soften, soothe, stifle, still, stuff,
   stupe, subdue, supersaturate, suppress, surfeit, tame, temper,
   tone down, tranquilize, tune down, underplay, weaken