hardness

noun

1. 1

   excessive sternness

   severity of character

   the harshness of his punishment was inhuman

2. 2

   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

3. 3

   devoid of passion or feeling; hardheartedness

4. 4

   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

5. 5

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