hardness

Meaning

Noun

• The quality of being hard.
• An instance of this quality; hardship.
• The quantity of calcium carbonate dissolved in water, usually expressed in parts per million (ppm).
• The resistance to scratching, cutting, indentation or abrasion of a metal or other solid material.
• The penetrating ability of electromagnetic radiation, such as x-rays; generally, the shorter the wavelength, the harder and more penetrating the radiation.
• The measure of resistance to damage of a facility, equipment, installation, or telecommunications infrastructure when subjected to attack.

Origin

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