The Collaborative International Dictionary of English v.0.48:

Lenitive \Len"i*tive\ (-t[i^]v), a. [Cf. F. l['e]nitif. See
   Lenient.]
   Having the quality of softening or mitigating, as pain or
   acrimony; assuasive; emollient.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Lenitive \Len"i*tive\, n. [Cf. F. l['e]nitif.]
   1. (Med.)
      (a) A medicine or application that has the quality of
          easing pain or protecting from the action of
          irritants.
      (b) A mild purgative; a laxative.
          [1913 Webster]

   2. That which softens or mitigates; that which tends to allay
      passion, excitement, or pain; a palliative.
      [1913 Webster]

            There is one sweet lenitive at least for evils,
            which Nature holds out; so I took it kindly at her
            hands, and fell asleep.               --Sterne.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lenitive
    adj 1: moderating pain or sorrow by making it easier to bear
           [syn: alleviative, alleviatory, lenitive,
           mitigative, mitigatory, palliative]
    n 1: remedy that eases pain and discomfort

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "lenitive":
   alleviating, alleviative, alleviator, altering, analgesic,
   anesthetic, anodyne, assuager, assuasive, balm, balmy, balsam,
   balsamic, benumbing, bounding, brilliantine, calmant, calmative,
   cathartic, chrism, cleansing, cold cream, collyrium, cream,
   cushion, deadening, demulcent, dolorifuge, dulling, easing,
   embrocation, emollient, extenuating, extenuatory, eye-lotion,
   eyewash, face cream, hand lotion, inunction, inunctum, lanolin,
   limitative, limiting, lotion, lubricant, lubricating,
   lubricational, lubricative, mitigating, mitigative, mitigator,
   mitigatory, moderator, modificatory, modifying, modulator,
   modulatory, mollifier, nard, numbing, ointment, pacificator,
   pacifier, pain-killing, palliative, peacemaker, pomade, pomatum,
   purgative, qualificative, qualificatory, qualifying, relieving,
   remedial, restraining hand, restricting, restrictive, salve,
   sedative, shock absorber, softening, soother, soothing,
   soothing syrup, spikenard, stabilizer, subduing, temperer,
   tranquilizer, unction, unguent, unguentum, wiser head