subside

Concise Oxford English Dictionary © 2008 Oxford University Press:
subside/səbˈsʌɪd/

▶verb

• 1 become less intense, violent, or severe.

  ■ (subside into) give way to (an overwhelming feeling).

• 2 (of water) go down to a lower or the normal level.

  ■ (of a swelling) reduce until gone.

• 3 (of a building) sink lower into the ground.

  ■ (of the ground) cave in; sink.

  ■ informal sink into a sitting, kneeling, or lying position.

– origin C17: from L. subsidere, from sub- ‘below’ + sidere ‘settle’.