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

• adversity
• asperity
• difficulty
• hardship
• rigor

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

Routine tests are ran every few hours to check water quality through pH, chlorine, phosphate, fluoride, alkalinity, total hardness, calcium hardness, turbidity and the Langelier Saturation Index, which determines water balance. —Olivia Stevens, Chicago Tribune, 30 Apr. 2025

Also add calcium chloride if the water's calcium level (hardness) is too low. —Brandee Gruener, Southern Living, 21 Apr. 2025

For street skating, a hardness of around 99a will be most suitable, while longboarders will want something around 80a. —Bestreviews, Mercury News, 17 Apr. 2025

The ultrathin blade made of Japanese carbon steel won't get discolored as easily as others, but the lack of information regarding the hardness of its blade gives me pause as to its performance in the long term. —Molly Higgins, Wired News, 2 May 2025

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