fall_off
1. [ verb ] come off
Examples:

"This button had fallen off"

Related terms: detach
2. [ verb ] fall heavily or suddenly; decline markedly
Synonyms: sink slump
Examples:

"The real estate market fell off"

Related terms: drop sink slump
3. [ verb ] diminish in size or intensity
Synonyms: fall_away
Related terms: disappear slump
Similar spelling:   falloff
  Falbo