1. Fall slowly to a stable position, usually on a surface or the ground
   "dust settled down on the roofs";
   - settle
    
2. Become settled or established and stable in one's residence or life style
   "He finally settled down";
   - settle, root, take root, steady down
    
3. Become quiet or calm, especially after a state of agitation
   "It took a while after the baby was born for things to settle down again";
   - calm, calm down, cool off, chill out [informal], simmer down [informal], cool it [informal], wind down, take a chill pill [informal], take it easy [informal]

Derived forms: settles down, settled down, settling down

Type of: change state, lay, place, pose, position, put, set, stabilise [Brit], stabilize, turn