hardness

Noun

hardness (countable and uncountable, plural hardnesses)

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, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Job 38:37–38
2. An instance of this quality; hardship.
3. The quantity of calcium carbonate dissolved in water, usually expressed in parts per million (ppm).
4. The resistance to scratching, cutting, indentation or abrasion of a metal or other solid material.
5. The penetrating ability of electromagnetic radiation, such as x-rays; generally, the shorter the wavelength, the harder and more penetrating the radiation.
6. The measure of resistance to damage of a facility, equipment, installation, or telecommunications infrastructure when subjected to attack.
7. (countable) A measure of how hard a material is.
   • The hardness of the material was high.
   • “This material has a specific hardness and is chemically very stable. It forms naturally from calcium alone, but bacteria accelerate the transformation into calcium carbonate,” explains Alejandro Montesinos, head of the Decarbonization, Climate Change, and Circular Economy Research Group at Tec de...2024 August 6, Ricardo Treviño, “Self-Healing Concrete Help Buildings Seal Themselves”, in TecScience, archived from the original on 19 Jan 2025