Definition of: hardness

(härd′nis) noun
1. The state of being hard.
2. Unyieldingness of spirit; insensitivity; callousness.
3. A property of water that contains mineral salts.
4. Med. Tension: said of the pulse.
5. In art, harsh effect or treatment.
6. That quality of a mineral that resists scratching: see MOHS SCALE.
7. The toughness of a metal or alloy: see BRINELL HARDNESS.
8. Physics A high-penetrating power of X-rays or other forms of radiant energy.