Failure:
* Bomb: This is a very strong synonym for "flop," implying a complete and utter failure.
* Disappointment: This implies that something did not meet expectations.
* Bust: This is a less formal synonym for "flop," meaning something was unsuccessful.
* Fizzle: This suggests a slow and gradual decline in success.
* Misfire: This suggests that something failed to achieve its intended effect.
Falling:
* Collapse: This is a more dramatic synonym for "flop" and suggests a sudden and forceful fall.
* Topple: This suggests that something is falling over.
* Plummet: This is a synonym for "flop" that suggests a rapid and uncontrolled descent.
* Lurch: This suggests a sudden and awkward movement.
Sound:
* Thud: This is a synonym for "flop" that refers to the sound of something falling heavily.
* Plop: This is a synonym for "flop" that refers to the sound of something falling lightly.
To choose the best synonym, consider the specific situation and the nuance you want to convey.