verb (v)

• lessen or to try to lessen the seriousness or extent of(verb.communication)

  Synonym:
  extenuate, palliate
  

  source: wordnet30
• make less severe or harsh(verb.change)

  Synonym:
  mince, moderate, soften
  

  source: wordnet30
• To make less severe, intense, harsh, rigorous, painful, etc.; to soften; to meliorate; to alleviate; to diminish; to lessen; as, to mitigate heat or cold; to mitigate grief.(verb)

  source: webster1913