What does hardener mean?
A hardener is, most commonly, a substance added to another material to make it harder, more rigid, or able to set. It is especially important in manufacturing and construction: epoxy hardeners react with resin to form a rigid material, while concrete hardeners help new surfaces resist wear and abrasion. In personal-care products, a hardener may promote the setting of a coating or gel. The word can also be understood more broadly as an agent whose role is to make something tougher or more durable, although that use is much less frequent. Unlike the related verb harden, hardener names the thing that performs the hardening function. Its technical associations can sound industrial, but the word is also familiar in nail products, crafts, coatings, and do-it-yourself contexts. A hardener does not always make a material harder merely by being added; it may trigger a curing reaction, supply a cross-linking component, or otherwise cause the material to set.
nounA substance added to another material to make it harder, more rigid, or able to set. More broadly, a person, thing, or substance whose function is to make something hard or tough.
- A substance or reagent that causes another material to become harder, more rigid, or set.
- A person, object, or process whose role is to make something hard or tough.
"The epoxy resin must be mixed thoroughly with its hardener before application."
"Mix the epoxy resin thoroughly with its hardener before applying it."
"This concrete hardener helps the new patio withstand heavy foot traffic."
The standard plural of the noun, used when referring to multiple hardening agents or products.
"The laboratory stocks several hardeners for different coatings."
A hardener does not necessarily make a material harder just by being added; it may trigger a curing reaction that makes the material set.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hardener come from?
Hardener was formed in English by adding the agentive suffix -er to harden. Harden combines hard with the verb-forming suffix -en, while hard continues Old English heard, an adjective meaning solid, tough, or severe. Related English forms include hardness, hardship, and hardly, all reflecting the same Germanic root.
Related word forms
How hardener is actually used
The word is especially common in technical, manufacturing, construction, and craft contexts. It usually names a reagent or component rather than the process itself; in general English, the broader sense of an agent that makes something tough is comparatively uncommon.