1. To sit, or to lie down heavily in a sudden, awkward way by relaxing the muscles and letting the body fall: He flopped down onto the couch while she flopped into the stuffed chair with a sigh.
2. To move limply, or heavily; to swing and to move in a loose, awkward, or uncontrolled way: The curtains were flopping around in the breeze which was coming through the open windows.
3. To fail completely; to be completely unsuccessful: The play flopped, or bombed, and all of their attempts to set things right also flopped miserably.

To execute a poorly done dive in which the front of the body lands flat on the surface of the water: Orville belly-flopped into the swimming pool right after his sister.

1. To undergo a complete turn around regarding a position or policy while trying to justify the change in the position: The presidential candidate kept flip-flopping on whether he would raise or lower income taxes.
2. Primarily in Britain, to undertake a "U" turn: The driver of the car ahead of Charles tried to flip-flop in a NO U-TURN zone and she was stopped by the police.