hardness

(n) the property of being rigid and resistant to pressure; not easily scratched; measured on Mohs scale
(n) a quality of water that contains dissolved mineral salts that prevent soap from lathering
- the costs of reducing hardness depend on the relative amounts of calcium and magnesium compounds that are present
(n) devoid of passion or feeling; hardheartedness callousness, unfeelingness, callosity, insensibility,
(n) 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
ruggedness,
(n) excessive sternness
- severity of character
- the harshness of his punishment was inhuman
- the rigors of boot camp
inclemency, rigorousness, rigourousness, rigor, rigour, harshness, severeness, severity, stiffness,

callousness unfeelingness callosity insensibility ruggedness inclemency rigorousness rigourousness rigor rigour harshness severeness severity stiffness

softness