settle down in WordNet English dictionary

1. become quiet or calm, especially after a state of agitation
   "After the fight both men need to cool off."; "It took a while after the baby was born for things to settle down again."
   calm  calm down  cool off  chill out  simmer down  settle down  cool it 
   
2. become settled or established and stable in one's residence or life style
   "He finally settled down"
   settle  root  take root  steady down  settle down 
   
3. settle into a position, usually on a surface or ground
   "dust settled on the roofs"
   settle  settle down 
   

settle down in English Wiktionary