What is the meaning of Pitfall?

A potential, unsuspected, hidden problem, hazard, or danger that is easily encountered but not immediately obvious.

A type of trap consisting of a concealed pit in the ground, which the victim is supposed to fall into and not be able to get out from.

An antipattern.

Subsidence below ground in a mine, which can cause the ground level above to drop.

Source: wiktionary.org