--verb usually used with object (verb: tranquilize; 3rd person present: tranquilizes; past tense: tranquilized; past participle: tranquilized; gerund or present participle: tranquilizing)

1. to make calm or still.
2. to cause to be calm or quiet as by administering a sedative to.
How to use "tran·quil·ize"?
Allay and alleviate are closely kindred in signification, and have been often interchanged in usage. But, in strictness, to allay is to lay to rest, quiet or soothe that which is excited; to alleviate, on the other hand, is to lighten a burden. We allay suffering by using means to soothe and tranquilize the sufferer; we alleviate suffering by doing something toward removal of the cause, so that there is less to suffer; where the trouble is wholly or chiefly in the excitement, to allay the excitement is virtually to remove the trouble: to allay rage or panic; we alleviate poverty, but do not allay it. Pacify, directly from the Latin, and appease, from the Latin through the French, signify to bring to peace; to mollify is to soften; to calm, quiet, or tranquilize is to make still; compose, to place together, unite, adjust to a calm and settled condition; to soothe (originally to assent to, humor) is to bring to pleased quietude. We allay excitement, appease a tumult, calm agitation, compose our feelings or countenance, pacify the quarrelsome, quiet the boisterous or clamorous, soothe grief or distress. Compare ALLEVIATE.
Synonyms
  • alleviate - to provide physical relief, as from pain.
  • compose - to form the substance of. "Greed and ambition composed his personality."
  • quiet - characterized by an absence or near absence of agitation or activity. "A quiet life."
  • still - with reference to action or condition; without change, interruption, or cessation. "It's still warm outside."
  • appease - to cause to be more favorably inclined; to gain the good will of.
  • mollify - to cause to be more favorably inclined; to gain the good will of. "She managed to mollify the angry customer."
  • soothe - to cause to feel better. "The medicine soothes the pain of the inflammation."
  • tranquilize - to make calm or still.
  • calm - not agitated; without losing self-possession. "Spoke in a calm voice."
  • pacify - to fight violence and try to establish peace in (a location). "The U.N. troops are working to pacify Bosnia."
Antonyms
  • agitate - to try to stir up public opinion.
  • excite - to stir feelings in. "Excite the audience."
  • kindle - to catch fire. "The dried grass of the prairie kindled, spreading the flames for miles."
  • rouse - to cause to become awake or conscious. "He was roused by the drunken men in the street."
  • stir up - to try to stir up public opinion.
  • arouse - to call forth (emotions, feelings, and responses). "Arouse pity."
  • fan - an enthusiastic devotee of sports.
  • provoke - to evoke or provoke to appear or occur. "Her behavior provoked a quarrel between the couple."
  • stir - to move an implement through. "Stir the soup."

"Tranquilize" is a song by Las Vegas-based rock band, The Killers featuring Lou Reed. The song was written by Brandon Flowers and it is featured on the compilation album Sawdust.