English edit

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Etymology edit

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

Pronunciation edit

Noun edit

hardness (countable and uncountable, plural hardnesses)

  1. The quality of being hard.
  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.

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