flop

Exactly.

“he fell flop on his face”

Fail utterly; collapse.

Fall loosely.

“He flopped into a chair”

Fall suddenly and abruptly.

Someone who is unsuccessful.

A complete failure.

“the play was a dismal flop”

The act of throwing yourself down.

“he landed on the bed with a great flop”

An arithmetic operation performed on floating-point numbers.

“this computer can perform a million flops per second”