a material that hardens another, as an alloy added to iron to make steel.
the process of becoming hard or rigid.

Origin of hardening

First recorded in 1620–30; harden + -ing1



verb (used with object)

to make hard or harder: to harden steel.
to make pitiless or unfeeling: to harden one's heart.
to make rigid or unyielding; stiffen: The rigors of poverty hardened his personality.
to strengthen or confirm, especially with reference to character, intentions, feelings, etc.; reinforce.
to make hardy, robust, or capable of endurance; toughen.
Military. to reinforce the structure of (a military or strategic installation) to protect it from nuclear bombardment.

verb (used without object)

to become hard or harder.
to become pitiless or unfeeling.
to become rigid or unyielding; stiffen: His personality hardened over the years.
to become confirmed or strengthened: His resistance hardened.
to become inured or toughened: The troops hardened under constant fire.
Commerce. (of a market, prices, etc.)
  1. to cease to fluctuate; firm: When the speculators withdrew from the market, the prices hardened.
  2. to rise higher.

Origin of harden

Middle English word dating back to 1150–1200; see origin at hard, -en1
Related formshard·en·a·ble, adjectivehard·en·a·bil·i·ty, nouno·ver·hard·en, verbpre·hard·en, verb (used with object)re·hard·en, verbun·hard·en, verb (used with object)un·hard·en·a·ble, adjective

Synonyms for harden

Antonyms for harden

1. soften. 4. weaken.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for hardening

crystallization, setting, solidification

Examples from the Web for hardening

Contemporary Examples of hardening

Historical Examples of hardening

  • They were street boys; their lives had been spent in a hardening atmosphere.

  • He was hardening his throat, and so slept with a wet towel about it.


    Mary Roberts Rinehart

  • Blessed ignorance of the hardening influences of the coming years!

    The First Violin

    Jessie Fothergill

  • Cf. Joseph and his brethren for this hardening of his heart.



  • The whole year round the thorn has been hardening and sharpening.

    Parables of the Cross

    I. Lilias Trotter

British Dictionary definitions for hardening



the act or process of becoming or making hard
a substance added to another substance or material to make it harder




to make or become hard or harder; freeze, stiffen, or set
to make or become more hardy, tough, or unfeeling
to make or become stronger or firmerthey hardened defences
to make or become more resolute or sethardened in his resolve
(intr) commerce
  1. (of prices, a market, etc) to cease to fluctuate
  2. (of price) to rise higher




a rough fabric made from hards
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 hardening



c.1200 (replacing Old English heardian) "to make (something) hard," from hard + -en (1). Meaning "to become hard" is late 14c. Related: Hardened (figurative sense of "unfeeling" is from late 14c.); hardening.

Online Etymology Dictionary, © 2010 Douglas Harper