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

It's recommended to clean your dishwasher filter every 3-6 months, depending on your usage frequency and water hardness. — Patricia Shannon, Southern Living, 9 July 2026

For over 20 years, this question has ranked among the biggest open problems in the field of quantum complexity theory, which studies the intrinsic hardness of quantum problems. — Ben Brubaker, Quanta Magazine, 6 July 2026

Grade 5 titanium is notoriously difficult to work with, its hardness rapidly degrading cutting tools and leaving little margin for error. — Richard Mille Contributor, Forbes.com, 25 June 2026

The new method led to a classification system that ranks a meteoroid's hardness. — Eric Lagatta, USA Today, 17 June 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