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 new method led to a classification system that ranks a meteoroid's hardness. —Eric Lagatta, USA Today, 17 June 2026

An unexpected discovery Diamond is valued in advanced technology because of its exceptional hardness, optical properties, and thermal conductivity (Tc). —Georgina Jedikovska, Interesting Engineering, 16 June 2026

The field crew tests the pitch daily for hardness, traction and moisture levels. —Tim Newcomb, Forbes.com, 13 June 2026

It's recommended to clean your dishwasher filter every 3-6 months, depending on your usage frequency and water hardness. —Patricia Shannon, Southern Living, 12 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