subside

verb

1. 1

   wear off or die down

   The pain subsided

2. 2

   descend into or as if into some soft substance or place

   He sank into bed

   She subsided into the chair

3. 3

   sink down or precipitate

   the mud subsides when the waters become calm

4. 4

   sink to a lower level or form a depression

   the valleys subside