subside

(verb) wear off or die down. Synonyms: lessen. Example: "The pain subsided."

(verb) sink to a lower level or form a depression. Example: "The valleys subside."

(verb) sink down or precipitate. Synonyms: settle. Example: "The mud subsides when the waters become calm."

(verb) descend into or as if into some soft substance or place. Synonyms: sink. Examples: "He sank into bed." "She subsided into the chair."