quieten in WordNet English dictionary

1. make calm or still
   "quiet the dragons of worry and fear"
   calm  calm down  quiet  tranquilize  tranquillize  tranquillise  quieten  lull  still 
   
2. cause to be quiet or not talk
   "Please silence the children in the church!"
   hush  quieten  silence  still  shut up  hush up 
   
3. become quiet or quieter
   "The audience fell silent when the speaker entered"
   quieten  hush  quiet  quiesce  quiet down  pipe down 
   

quieten in English Wiktionary