TRANQUILLIZE

sedate, calm, tranquilize, tranquillize, tranquillise

(verb) cause to be calm or quiet as by administering a sedative to; “The patient must be sedated before the operation”

calm, calm down, quiet, tranquilize, tranquillize, tranquillise, quieten, lull, still

(verb) make calm or still; “quiet the dragons of worry and fear”

Source: WordNet® 3.1

Verb

tranquillize (third-person singular simple present tranquillizes, present participle tranquillizing, simple past and past participle tranquillized)

Alternative spelling of tranquilize

Source: Wiktionary

Tran"quil*ize, Tran"quil*lize, v. t. [imp. & p. p. Tranquilized or Tranquilliized; p. pr. & vb. n. Tranquilizing or Tranquillizing.] Etym: [Cf. F. tranquilliser.]

Definition: 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.

Syn.

– To quiet; compose; still; soothe; appease; calm; pacify.

Source: Webster’s Unabridged Dictionary 1913 Edition