verb (v)

• become quiet or calm, especially after a state of agitation(verb.emotion)

  Synonym:
  calm, chill out, cool it, cool off, settle down, simmer down
  

  source: wordnet30
• make calm or still(verb.emotion)

  Synonym:
  calm, lull, quiet, quieten, still, tranquilize, tranquillise, tranquillize
  Antonym:
  agitate, charge, charge up, commove, excite, rouse, turn on
  

  source: wordnet30
• become quiet or less intensive(verb.change)

  Synonym:
  lull
  

  source: wordnet30