Hardness Common

the property of being rigid and resistant to pressure; not easily scratched; measured on Mohs scale

"The geologist tapped the sample against a steel file to confirm its hardness before assigning it a rating on the Mohs scale."

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"

devoid of passion or feeling; hardheartedness

"Her refusal to help her own family in need revealed a shocking hardness that made everyone wonder where her compassion had gone."

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"

excessive sternness

"severity of character"

"the harshness of his punishment was inhuman"

"the rigors of boot camp"

The quality of being hard.

"The hardness of the diamond made it perfect for cutting through the toughest metals."