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
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
Diamond grit is used by industrial manufacturers — including in the semiconductor, automotive and energy sectors — for its hardness properties.
—
Dallas Morning News, 18 Feb. 2026
As his younger, more romantic self, that hardness never quite goes away.
—Bilge Ebiri, Vulture, 16 Feb. 2026
Known for its hardness and high melting point, petalite is already valued in heat- and scratch-resistant glass and ceramics.
—Jijo Malayil, Interesting Engineering, 9 Feb. 2026
In one-of-a-kind high-jewelry chokers and necklaces, the design is rendered in black diamond-like carbon, or DLC—a high-tech material known for its exceptional hardness and scratch-resistance that is often used in watchmaking—and combined with diamonds and yellow gold for an avant-garde look.
—Paige Reddinger, Robb Report, 7 Feb. 2026
See All Example Sentences for hardness
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Dallas Morning News, 18 Feb. 2026
As his younger, more romantic self, that hardness never quite goes away.
—Bilge Ebiri, Vulture, 16 Feb. 2026
Known for its hardness and high melting point, petalite is already valued in heat- and scratch-resistant glass and ceramics.
—Jijo Malayil, Interesting Engineering, 9 Feb. 2026
In one-of-a-kind high-jewelry chokers and necklaces, the design is rendered in black diamond-like carbon, or DLC—a high-tech material known for its exceptional hardness and scratch-resistance that is often used in watchmaking—and combined with diamonds and yellow gold for an avant-garde look.
—Paige Reddinger, Robb Report, 7 Feb. 2026
See All Example Sentences for hardness
Cite this Entry
“Hardness.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hardness. Accessed 23 Feb. 2026.
Copy CitationKids 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
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