hardness

noun

hard·​ness ˈhärd-nəs How to pronounce hardness (audio)
Synonyms of hardnessnext
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

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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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Depending on your water hardness, the humidifier will need a deep cleaning from time to time. — John R. Delaney, PC Magazine, 28 Apr. 2026 The new method led to a classification system that ranks a meteoroid's hardness. — Eric Lagatta, USA Today, 17 June 2026 Its replaceable filters will help reduce water hardness. — Bestreviews, Mercury News, 30 Apr. 2026 Water hardness is measured by the milligrams of calcium carbonate per liter of water(mg/L). — Mary Marlowe Leverette, Southern Living, 23 June 2026 See All Example Sentences for hardness

Word History

First Known Use

before the 12th century, in the meaning defined at sense 1

Time Traveler
The first known use of hardness was before the 12th century

Phrases Containing hardness

Rhymes for hardness

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Browse Nearby Words

hardmouthed
hardness
hardnose
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Cite this Entry

“Hardness.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hardness. Accessed 7 Jul. 2026.

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Kids Definition

hardness

noun
hard·​ness ˈhärd-nəs How to pronounce hardness (audio)
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

More from Merriam-Webster on hardness

Nglish: Translation of hardness for Spanish Speakers

Britannica.com: Encyclopedia article about hardness

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