pitfall

noun

1. a lightly covered and unnoticeable pit prepared as a trap for people or animals.
2. any trap or danger for the unwary: the pitfall of excessive pride.

noun

1. an unsuspected difficulty or danger
2. a trap in the form of a concealed pit, designed to catch men or wild animals

n.c.1300, “concealed hole,” a type of animal trap, from pit (n.1) + fall (n.). Extended sense of “any hidden danger” is first recorded early 15c.