- the state or quality of being hard: the hardness of ice.
- a relative degree or extent of this quality: wood of a desirable hardness.
- that quality in water that is imparted by the presence of dissolved salts, especially calcium sulfate or bicarbonate.
- unfeelingness or jadedness; callousness.
- harshness or austerity, as of a difficult existence.
- ill will; bad feelings: There's a lot of hardness between those two boys.
- the comparative ability of a substance to scratch or be scratched by another.
- the measured resistance of a metal to indention, abrasion, deformation, or machining.
- the quality or condition of being hard
- one of several measures of resistance to indentation, deformation, or abrasion
- the quality of water that causes it to impair the lathering of soap: caused by the presence of certain calcium salts. Temporary hardness can be removed by boiling whereas permanent hardness cannot
