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
Synonyms
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
If necessary, place a resealable bag filled with ice over the stain to harden the sap first.
—
Jessica Bennett, Better Homes & Gardens, 10 Dec. 2024
Local utilities such as Austin Energy and CenterPoint Energy are also adding cleanup costs from storms and further costs necessary to harden their local distribution infrastructure to customers’ bills.
—Ed Hirs, Forbes, 9 Dec. 2024
Allen, the first Black star for a Phillies franchise that was the NL’s last to integrate, had a perspective hardened by his minor-league experience in Little Rock, Ark.
—Tyler Kepner, The Athletic, 9 Dec. 2024
Allow the snaps to cool on the tray for five minutes to harden up, then transfer to a wire rack and leave them to go completely cold.
—The Week Junior, theweek, 5 Dec. 2024
See all Example Sentences for harden 
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Jessica Bennett, Better Homes & Gardens, 10 Dec. 2024
Local utilities such as Austin Energy and CenterPoint Energy are also adding cleanup costs from storms and further costs necessary to harden their local distribution infrastructure to customers’ bills.
—Ed Hirs, Forbes, 9 Dec. 2024
Allen, the first Black star for a Phillies franchise that was the NL’s last to integrate, had a perspective hardened by his minor-league experience in Little Rock, Ark.
—Tyler Kepner, The Athletic, 9 Dec. 2024
Allow the snaps to cool on the tray for five minutes to harden up, then transfer to a wire rack and leave them to go completely cold.
—The Week Junior, theweek, 5 Dec. 2024
See all Example Sentences for harden
Dictionary Entries Near harden
Cite this Entry
“Harden.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harden. Accessed 16 Dec. 2024.
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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