[ hahrd-nis ]
See synonyms for hardness on Thesaurus.com
  1. the state or quality of being hard: the hardness of ice.

  2. a relative degree or extent of this quality: wood of a desirable hardness.

  1. that quality in water that is imparted by the presence of dissolved salts, especially calcium sulfate or bicarbonate.

  2. unfeelingness or jadedness; callousness.

  3. harshness or austerity, as of a difficult existence.

  4. South Midland U.S. ill will; bad feelings: There's a lot of hardness between those two boys.

  5. Mineralogy. the comparative ability of a substance to scratch or be scratched by another.: Compare Mohs scale.

  6. Metallurgy. the measured resistance of a metal to indention, abrasion, deformation, or machining.

Origin of hardness

First recorded before 900; Middle English hardnes, Old English heardnes; see hard, -ness

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use hardness in a sentence

British Dictionary definitions for hardness


/ (ˈhɑːdnɪs) /

  1. the quality or condition of being hard

  2. one of several measures of resistance to indentation, deformation, or abrasion: See Mohs scale, Brinell hardness number

  1. the quality of water that causes it to impair the lathering of soap: caused by the presence of certain calcium salts. Temporary hardness can be removed by boiling whereas permanent hardness cannot

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for hardness


[ härdnĭs ]

  1. A measure of how easily a mineral can be scratched. Hardness is measured on the Mohs scale.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.