hardness

noun7

1. •
   The quality of being hard.

   • Who can number the cloudes in wisedom? or who can stay the bottles of heauen, / When the dust groweeh^([sic – meaning groweth]) into hardnesse and the clods cleaue fast together? — 1611
2. •
   The resistance to scratching, cutting, indentation or abrasion of a metal or other solid material.
3. •
   The measure of resistance to damage of a facility, equipment, installation, or telecommunications infrastructure when subjected to attack.
4. •
   A measure of how hard a material is.

   • The hardness of the material was high.
5. •
   The quantity of calcium carbonate dissolved in water, usually expressed in parts per million (ppm).
6. •
   An instance of this quality; hardship.
7. •
   The penetrating ability of electromagnetic radiation, such as x-rays; generally, the shorter the wavelength, the harder and more penetrating the radiation.