behavior intended to please your parents; "their children were never very strong on obedience"; "he went to law school out of respect for his father's wishes"
the act of obeying; dutiful or submissive behavior with respect to another person
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