hardness

noun

1 the hardness of the ground:

firmness, solidity, stiffness, rigidity, denseness, inflexibility, inelasticity, resistance.

▷antonyms softness.

2 there was a core of calculating hardness to this man:

hard-heartedness, heartlessness, cold-heartedness, lack of compassion, lack of feeling, lack of sentiment, callousness, unkindness, flintiness, steeliness;

harshness, severity, strictness, sternness, toughness.

▷antonyms compassion, kindness.

hardness Oxford Dictionary of English