v. hard·ened, hard·en·ing, hard·ens
1. To make hard or harder: harden steel.
2. To enable to withstand physical or mental hardship: was hardened by years of working as a farmer.
3. To make unfeeling, unsympathetic, or callous: The betrayal hardened his heart against intimacy.
4. To make fixed, settled, or less subject to change: "The incident only hardened existing attitudes while vanquishing any hope of collaboration" (Philip Dray).
5. To make less vulnerable to attack by surrounding with earth or concrete: harden missile silos.
1. To become hard or harder.
2. To become fixed, settled, or less subject to change: "Her early skepticism has hardened into cynicism" (Kelly Braffet).
3. To become inured.
4. To take on a disapproving or severe appearance: His face hardened with suspicion.
5. To rise and become stable. Used of prices.
Synonyms: harden, acclimate, acclimatize, season, toughen
These verbs mean to make resistant to hardship, especially through continued exposure: was hardened to frontier life; is acclimated to the tropical heat; was acclimatized by long hours to overwork; became seasoned to life in prison; has become toughened by adversity.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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