hardened; hardening
ˈhärd-niŋ 
ˈhär-dᵊn-iŋ
1
: to make hard or harder
2
: to confirm in disposition, feelings, or action
especially
: to make callous
hardened his heart
3
4
: to protect from blast, heat, or radiation (as by a thick barrier or placement underground)
1
: to become hard or harder
2
a
: to become firm, stable, or settled
b
: to assume an appearance of harshness or severity
Her face hardened at the thought.
3
: to become gradually acclimatized to unfavorable conditions
—often used with off
plants hardened off before the first frost
Examples of harden in a Sentence
The presence of certain substances in the blood can cause the arteries to harden.
These additives are designed to harden the steel.
substances that can harden the arteries
The news has hardened opposition to the government.
He had been hardened by his years of military service.
Recent Examples on the Web
By foregrounding things like ancient waterways and table tennis, China is deploying a sophisticated brand of cultural statecraft designed to soften the edges of a hardening geopolitical landscape.
—
Xianda Huang, The Conversation, 15 Dec. 2025
Yet he's struggled to deliver on that promise, and his sweeping tariffs on imports ‒ and refusal to support extending expiring Obamacare subsidies ‒ have given Democrats ammunition to blame hardening costs on the president's policies.
—Joey Garrison, USA Today, 11 Dec. 2025
The realization seemed to harden their resolve, and jelled into one of the most efficient political movements to hit Washington in decades.
—Philip Elliott, Time, 11 Dec. 2025
Because the batter is scooped directly from a saucepan and left to set and harden on wax paper, the rounds often enrobe the pecan pieces to form bizarre shapes and a very particular creamy hue.
—Joey Skladany, Southern Living, 9 Dec. 2025
See All Example Sentences for harden
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Xianda Huang, The Conversation, 15 Dec. 2025
Yet he's struggled to deliver on that promise, and his sweeping tariffs on imports ‒ and refusal to support extending expiring Obamacare subsidies ‒ have given Democrats ammunition to blame hardening costs on the president's policies.
—Joey Garrison, USA Today, 11 Dec. 2025
The realization seemed to harden their resolve, and jelled into one of the most efficient political movements to hit Washington in decades.
—Philip Elliott, Time, 11 Dec. 2025
Because the batter is scooped directly from a saucepan and left to set and harden on wax paper, the rounds often enrobe the pecan pieces to form bizarre shapes and a very particular creamy hue.
—Joey Skladany, Southern Living, 9 Dec. 2025
See All Example Sentences for harden
Cite this Entry
“Harden.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harden. Accessed 19 Dec. 2025.
Copy CitationKids Definition
harden
verb
hard·en
ˈhärd-ᵊn
hardened; hardening
ˈhärd-niŋ
-ᵊn-iŋ
1
: to make or become hard or harder
2
: to make unfeeling or unsympathetic
hardened his heart
3
: to make or become hardy or strong
muscles hardened by exercise
4
: to protect from blast, heat, or radiation (as by a thick barrier or by placing underground)
hardened missile sites
5
a
: to become firm, stable, or settled
b
: to express harshness
hardener
noun
ˈhärd-nər,
-ᵊn-ər
Biographical Definition
Harden
2 of 2biographical name (2)
Maximilian 1861–1927 originally Felix Ernst Witkowski German writer
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