The Collaborative International Dictionary of English v.0.48:

Palliative \Pal"li*a*tive\, a. [Cf. F. palliatif.]
   Serving to palliate; serving to extenuate, mitigate, or
   alleviate.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Palliative \Pal"li*a*tive\, n.
   That which palliates; a palliative agent. --Sir W. Scott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

palliative
    adj 1: moderating pain or sorrow by making it easier to bear
           [syn: alleviative, alleviatory, lenitive,
           mitigative, mitigatory, palliative]
    n 1: remedy that alleviates pain without curing [syn:
         palliative, alleviant, alleviator]

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "palliative":
   alleviating, alleviative, alleviator, allowance, altering,
   analgesic, anesthetic, anodyne, apologetic, assuager, assuasive,
   balm, balmy, balsamic, benumbing, bounding, calmant, calmative,
   cathartic, cleansing, color, cushion, deadening, decontamination,
   demulcent, dolorifuge, dulling, easing, emollient, excusatory,
   excusing, extenuating, extenuating circumstances, extenuation,
   extenuative, extenuatory, gilding, gloss, justificatory,
   justifying, lenitive, limitative, limiting, mitigating, mitigation,
   mitigative, mitigator, mitigatory, moderator, modificatory,
   modifying, modulator, modulatory, mollifier, numbing, pacificator,
   pacifier, pain-killing, palliation, peacemaker, purgative,
   qualification, qualificative, qualificatory, qualifying, refuting,
   rehabilitative, relieving, remedial, restraining hand, restricting,
   restrictive, salve, sedative, shock absorber, softening, soother,
   soothing, soothing syrup, stabilizer, subduing, temperer,
   tranquilizer, varnish, vindicative, vindicatory, whitewash,
   whitewashing, wiser head