v.
   - become less intense, violent, or severe. 
▸
(subside into)
 give way to (an overwhelming feeling).
 - (of water) go down to a lower or the normal level. 
▸(of a swelling) reduce until gone.
 - (of a building) sink lower into the ground. 
▸(of the ground) cave in; sink.
 ▸informal sink into a sitting, kneeling, or lying position.
 
 
  Etymology
  C17: from L. subsidere, from sub- ‘below’ + sidere ‘settle’.