hardness

noun

hard·​ness ˈhärd-nəs 

1

: the quality or state of being hard

2

a

: the cohesion of the particles on the surface of a mineral as determined by its capacity to scratch another or be itself scratched compare mohs' scale

b

: resistance of metal to indentation under a static load or to scratching

Synonyms of hardness

• hardship
• difficulty

Examples of hardness in a Sentence

the hardness of a diamond

The wood's hardness makes it suitable for carving.

Recent Examples on the Web

Going into the study, the team hypothesized that pincers built for generating high crushing force would contain the highest levels of metal to provide maximum hardness, while enrichment in the weaker, slender pincers would be lower. —Jacek Krywko, ArsTechnica, 1 May 2026

Its replaceable filters will help reduce water hardness. —Bestreviews, Mercury News, 30 Apr. 2026

Depending on your water hardness, the humidifier will need a deep cleaning from time to time. —John R. Delaney, PC Magazine, 28 Apr. 2026

There’s an almost paradoxical tension between the lushness of the melody and the hardness of the drums, between something very raw and something very sophisticated. —New York Times, 28 Apr. 2026

Word History

First Known Use

before the 12th century, in the meaning defined at sense 1

Phrases Containing hardness

• Brinell hardness
• Brinell hardness number

Rhymes for hardness

• microhardness

Kids Definition

hardness

noun

hard·​ness ˈhärd-nəs 

1

: the quality or state of being hard

2

: the ability of a substance (as a mineral) to scratch another substance or be itself scratched