The term 'unexpected difficulty' can be described by four crossword solutions: SNAG (4 letters), PITFALL (7 letters), HITCH (5 letters), and pitf (4 letters). A SNAG is an unexpected obstacle or problem that arises, while a PITFALL is a hidden danger or difficulty. A HITCH is a minor problem or difficulty, and a pitf is a difficult situation or problem. All of these terms refer to unexpected difficulties that can arise in any situation.