verb (v)

• become quiet or quieter(verb.perception)

  Synonym:
  hush, pipe down, quiesce, quiet, quiet down
  

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

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

  source: wordnet30
• cause to be quiet or not talk(verb.change)

  Synonym:
  hush, hush up, shut up, silence, still
  Antonym:
  louden
  

  source: wordnet30