1. a person or thing that hardens.
  2. a substance mixed with paint or other protective covering to make the finish harder or more durable.
  3. Photography. a chemical used to raise the melting point of an emulsion.

Origin of hardener

First recorded in 1605–15; harden + -er1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for hardener

Historical Examples of hardener

  • She was a harmful woman, a destroyer of young tempers, a hardener of young hearts.

    Stage Confidences

    Clara Morris

  • Guet and guiv demand dhe (u) hardener, az boldly az gues and guilt.

  • A recent rival of tungsten both as a filament for lamps and hardener for steel is molybdenum.

    Creative Chemistry

    Edwin E. Slosson

British Dictionary definitions for hardener


  1. a person or thing that hardens
  2. a substance added to paint or varnish to increase durability
  3. an ingredient of certain adhesives and synthetic resins that accelerates or promotes setting
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

Word Origin and History for hardener

1610s, from harden + -er (1).

Online Etymology Dictionary, © 2010 Douglas Harper