What does hardness mean?
Hardness is the quality of being hard or difficult. Its most familiar physical sense refers to a material's firmness and resistance to scratching, pressure, or penetration, as in the hardness of steel or diamond. It can also describe the difficulty of a task or situation, or, in figurative use, the severity of a rule, punishment, or emotional manner. Water hardness is a more technical sense: it measures the presence of dissolved minerals, especially calcium and magnesium compounds, which affect soap use and scaling in pipes or boilers. The word is useful because it names a quality rather than a particular object or event. In technical writing, hardness is usually a measurable property, while in everyday language it can be vague, as in “the hardness of the competition” or “the hardness of his expression.”
nounHardness is the quality of being hard, especially the firmness of a material or the difficulty of a task or situation. It can also refer to severity, harshness, or the mineral content of water.
- The quality of being firm, solid, or resistant to physical pressure, impact, or penetration.
- The difficulty or complexity of a task, problem, or situation.
- Severity, harshness, or lack of leniency.
- The degree to which water contains dissolved mineral salts, especially calcium and magnesium compounds.
"The hardness of the steel made it well suited to construction."
"Diamond is valued for its exceptional hardness and resistance to scratching."
"The hardness of the examination made even well-prepared candidates anxious."
The plural is grammatically correct but uncommon; hardness is usually treated as an uncountable noun.
"The laboratory compared the hardnesses of samples from several batches."
In materials science, hardness is not the same as toughness: hardness resists scratching, while toughness resists breaking or fracture.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hardness come from?
Hardness is a Middle English formation from hard plus the suffix -ness. The adjective hard descends from Old English heard, an inherited Germanic word with senses including firm, solid, and difficult. Related English forms include harden and hardship, while hardy entered through Old French and is ultimately connected to the same Germanic family of words.
How hardness is actually used
Hardness is common in general and technical contexts. In discussions of policy, punishment, or personal conduct, it often implies severity or an unemotional attitude; in materials science and water treatment, it has specialized measurable meanings.
Easily confused with hardness
Hardness describes how firm, difficult, or severe something is, whereas hardiness describes the ability to withstand harsh conditions.