the quality of being difficult to do; "he assigned a series of problems of increasing hardness"; "the ruggedness of his exams caused half the class to fail"
the property of being rigid and resistant to pressure; not easily scratched; measured on Mohs scale
the quality of being difficult; "they agreed about the difficulty of the climb"
a factor causing trouble in achieving a positive result or tending to produce a negative result; "serious difficulties were encountered in obtaining a pure reagent"
a condition or state of affairs almost beyond one's ability to deal with and requiring great effort to bear or overcome; "grappling with financial difficulties"