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 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

Downstream lithography and ion implantation steps are also more demanding than for silicon, partly because SiC’s hardness complicates polishing and etch uniformity. —Aditya Jadhav, Interesting Engineering, 1 June 2026

Load size, water hardness, soil level and machine type all affect how much detergent your laundry actually needs per load. —Ryan Brennan may 14, Fort Worth Star-Telegram, 14 May 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