noun
                                                the property of being rigid and resistant to pressure
                                                
                                                                                                Examples
                                                
                                                                                                        - not easily scratched
- measured on Mohs scale
 
                                                                                        
                                                noun
                                                a quality of water that contains dissolved mineral salts that prevent soap from lathering
                                                
                                                                                                Examples
                                                
                                                                                                        - the costs of reducing hardness depend on the relative amounts of calcium and magnesium compounds that are present
 
                                                                                        
                                                noun
                                                devoid of passion or feeling
                                                                                                Synonyms
                                                
                                                
                                                                                                Examples
                                                
                                                                                                        - hardheartedness
 
                                                                                        
                                                noun
                                                the quality of being difficult to do
                                                                                                Synonyms
                                                
                                                
                                                                                                Examples
                                                
                                                                                                        - he assigned a series of problems of increasing hardness
- the ruggedness of his exams caused half the class to fail
 
                                                                                        
                                                noun
                                                excessive sternness
                                                                                                Synonyms
                                                
                                                
                                                                                                Examples
                                                
                                                                                                        - severity of character
- the harshness of his punishment was inhuman
- the rigors of boot camp