verb (v)

• make calm or still(verb.emotion)

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

  source: wordnet30
• cause to be calm or quiet as by administering a sedative to(verb.body)

  Synonym:
  calm, sedate, tranquillise, tranquillize
  Antonym:
  arouse, brace, energise, energize, perk up, stimulate
  

  source: wordnet30
• To render tranquil; to allay when agitated; to compose; to make calm and peaceful; as, to tranquilize a state disturbed by factions or civil commotions; to tranquilize the mind.(verb)

  source: webster1913