hardness

• hardnesse (obsolete)

From Middle English hardness, hardnesse, from Old English heardness, from heard + -ness. Equivalent to hard +‎ -ness.

• (General American) enPR: härdʹnəs, IPA^(key): /ˈhɑɹdnəs/
• (Received Pronunciation) IPA^(key): /ˈhɑːdnəs/

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• Hyphenation: hard‧ness

hardness (countable and uncountable, plural hardnesses)

1. The quality of being hard.
   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Job 38:37–38:

     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?

2. An instance of this quality; hardship.
3. (inorganic chemistry) 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. (physics) 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, engineering) A measure of how hard a material is

   The hardness of the material was high.

• hardiness

• “hardness”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.

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