pitfall
Pitfall (noun) means a hidden hole dug in the ground as a trap, so that whatever falls in cannot climb out.
Etymology
First recorded in the 14th century, formed from pit and fall in the sense "pit trap, pit snare", from Old English fealle ("trap, snare"), from Proto-Germanic *fallą, *fallaz ("a fall, trap"), from Proto-Indo-European *(s)pōl-. It is cognate with German Falle ("trap, snare").