Synonyms of harden

harden

verb

ˈhär-dᵊn 

1

as in to freeze

to become physically firm or solid

the glue begins to harden as soon as it is exposed to air

Synonyms & Similar Words

• freeze
• stiffen
• solidify
• congeal
• concrete
• indurate
• firm (up)
• set
• thicken
• gel
• crystallize
• encrust
• coagulate
• cake
• gelatinize
• jell
• calcify
• ossify
• petrify
• rigidify
• callus
• anneal
• temper
• clot
• jelly
• gelate
• case-harden

Antonyms & Near Antonyms

• soften
• liquefy
• melt
• dissolve
• thaw
• smelt
• fuse
• flux
• unfreeze
• deliquesce

2

as in to strengthen

to make able to withstand physical hardship, strain, or exposure

pioneer women who had been hardened by years of living on the plains

Synonyms & Similar Words

• strengthen
• fortify
• toughen
• steel
• inure
• adjust
• season
• indurate
• adapt
• bolster
• reinforce
• acclimate
• temper
• anneal
• invigorate
• enforce
• brace
• vitalize
• acclimatize
• immunize
• accustom
• buttress
• habituate
• condition
• boost
• break in
• prop (up)
• support
• naturalize
• train
• forearm
• limber (up)

Antonyms & Near Antonyms

• soften
• weaken
• exhaust
• sap
• emasculate
• cripple
• incapacitate
• hamstring
• sensitize
• enfeeble
• enervate
• debilitate

3

as in to toughen

to increase the ability of (as a muscle) to exert physical force

arm muscles that were hardened by all the years of casting and hauling his fishing nets

Synonyms & Similar Words

• strengthen
• toughen
• fortify
• beef (up)
• temper
• anneal
• energize
• invigorate
• tone (up)
• vitalize
• firm (up)
• restrengthen

Antonyms & Near Antonyms

• weaken
• hurt
• impair
• paralyze
• cripple
• injure
• harm
• damage
• debilitate
• enervate
• enfeeble
• undermine
• incapacitate
• break down
• wear out
• undercut
• sap

4

as in to stiffen

to make more harsh, uncompromising, or severe

the government hardened restrictions on travel to and from the war-torn nation

Synonyms & Similar Words

• stiffen
• strengthen
• toughen
• harshen

Antonyms & Near Antonyms

• ease
• lessen
• soften
• ameliorate
• moderate

Example Sentences

Recent Examples of harden

However, some experts are concerned about how the roughly year-long effort to modify the aircraft may not have been sufficient to fully harden it for operations in high-threat airspace. — Alexandra Skores, CNN Money, 10 July 2026

Instead of building parts one layer at a time, the system hardens the printing material all at once, producing seamless structures. — Neetika Walter, Interesting Engineering, 10 July 2026

Folks like my grandparents were reflective of that era, necessarily hardened, with no idea how to be soft. — John Todd, Outdoor Life, 9 July 2026

The cancellation of the MOU was a campaign promise of Anutin’s government, capitalizing on a nationalist mood hardened by the clashes over land borders. — Ken Silverstein, Forbes.com, 7 July 2026