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.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.