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
Democratic policies regarding immigration have evolved as attitudes, even among Latinos, have hardened after record border crossings during former President Joe Biden‘s administration.
—
Naomi Lim, The Washington Examiner, 13 June 2025
Now, your union advised agricultural employers to harden work sites.
—A Martínez, NPR, 13 June 2025
Without complementary requirements for hardening the homes themselves, widespread clearing of landscaping immediately around homes could do little to reduce risk and could even aggravate the danger.
—Max Moritz, Mercury News, 5 June 2025
The story centers around a woman who is hardened by life after being left at the altar on her wedding day.
—Armando Tinoco, Deadline, 27 May 2025
See All Example Sentences for harden
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Naomi Lim, The Washington Examiner, 13 June 2025
Now, your union advised agricultural employers to harden work sites.
—A Martínez, NPR, 13 June 2025
Without complementary requirements for hardening the homes themselves, widespread clearing of landscaping immediately around homes could do little to reduce risk and could even aggravate the danger.
—Max Moritz, Mercury News, 5 June 2025
The story centers around a woman who is hardened by life after being left at the altar on her wedding day.
—Armando Tinoco, Deadline, 27 May 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 2 Jul. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share