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

The best rocks are hard, non-porous rocks with a non-gritty surface, ideally a seven on the Mohs’ hardness scale. — Bestreviews, Mercury News, 5 Aug. 2026

In this form, boron nitride becomes what scientists call a superhard material, second in hardness to diamond. — Robin MacAluso, The Conversation, 3 Aug. 2026

The Army therefore needs materials with approximately the same electromagnetic properties as those tissues, not just the same weight, hardness, or softness. — Christopher McFadden, Interesting Engineering, 25 July 2026

On the Mohs scale of hardness, which runs from 1 to 10, andesite is a 7, similar to quartz and more resistant than a steel nail. — Stephanie Pappas, Scientific American, 23 July 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