Definitions of subside:

• verb:   wear off or die down

  Example: "The pain subsided"

• verb:   sink down or precipitate

  Example: "The mud subsides when the waters become calm"

• verb:   sink to a lower level or form a depression

  Example: "The valleys subside"

• verb:   descend into or as if into some soft substance or place

  Example: "She subsided into the chair"