1. fell, dropped, or threw oneself down heavily and carelessly
2. failed completely, especially in entertainment or business
Usage: informal
3. moved or swung loosely back and forth

Examples

• She flopped onto the couch after a long day at work.
• The tired dog flopped down in the shade.
• The movie flopped at the box office despite heavy promotion.
• His hair flopped over his eyes as he ran.
• The fish flopped around on the deck of the boat.
• The new restaurant flopped within six months.
• He flopped into bed without changing his clothes.