difficultness (n)
difficulty (n)

Definition: the quality of being difficult
Example: they agreed about the difficulty of the climb.

difficulty (n)

Definition: a condition or state of affairs almost beyond one's ability to deal with and requiring great effort to bear or overcome
Example: grappling with financial difficulties.

difficulty (n)

Definition: a factor causing trouble in achieving a positive result or tending to produce a negative result
Example: serious difficulties were encountered in obtaining a pure reagent.

straits (n)
strait (n)
pass (n)

Definition: a bad or difficult situation or state of affairs