The Collaborative International Dictionary of English v.0.48:

Palliate \Pal"li*ate\, v. t. [imp. & p. p. Palliated; p. pr. &
   vb. n. Palliating.]
   1. To cover with a mantle or cloak; to cover up; to hide.
      [Obs.]
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            Being palliated with a pilgrim's coat. --Sir T.
                                                  Herbert.
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   2. To cover with excuses; to conceal the enormity of, by
      excuses and apologies; to extenuate; as, to palliate
      faults.
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            They never hide or palliate their vices. --Swift.
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   3. To reduce in violence; to lessen or abate; to mitigate; to
      ease without curing; as, to palliate a disease.
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            To palliate dullness, and give time a shove.
                                                  --Cowper.
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   Syn: To cover; cloak; hide; extenuate; conceal.

   Usage: To Palliate, Extenuate, Cloak. These words, as
          here compared, are used in a figurative sense in
          reference to our treatment of wrong action. We cloak
          in order to conceal completely. We extenuate a crime
          when we endeavor to show that it is less than has been
          supposed; we palliate a crime when we endeavor to
          cover or conceal its enormity, at least in part. This
          naturally leads us to soften some of its features, and
          thus palliate approaches extenuate till they have
          become nearly or quite identical. "To palliate is not
          now used, though it once was, in the sense of wholly
          cloaking or covering over, as it might be, our sins,
          but in that of extenuating; to palliate our faults is
          not to hide them altogether, but to seek to diminish
          their guilt in part." --Trench.
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