hardness: Meaning and Definition of

hard•ness

1. the state or quality of being hard: the hardness of ice.
2. a relative degree or extent of this quality: wood of a desirable hardness.
3. that quality in water that is imparted by the presence of dissolved salts, esp. calcium sulfate or bicarbonate.
4. unfeelingness or jadedness; callousness.
5. harshness or austerity, as of a difficult existence.
6. ill will; bad feelings: There's a lot of hardness between those two boys.
7. the comparative ability of a substance to scratch or be scratched by another. Cf. Mohs scale.
8. the measured resistance of a metal to indention, abrasion, deformation, or machining.