tranquillize

Verb

• cause to be calm or quiet as by administering a sedative to
  • The patient must be sedated before the operation
    

• make calm or still
  • quiet the dragons of worry and fear
    

Related words

• Synonyms: 
  sedate , calm , tranquilize , tranquillise , calm down , quiet , quieten , lull , still
• Antonyms: 
  stimulate , arouse , brace , energize , energise , perk up , agitate , rouse , turn on , charge , commove , excite , charge up