harden has definitions from the field of metallurgy
1
[ verb ] become hard or harder

Synonyms

indurate

Examples

"The wax hardened"

Used in print

(Hal Kelly, "Build Hotei"...)

When the resin has hardened , mix up another batch with a pigment added if you wish .

Be sure it is well saturated and_then allow it to harden .

When the whole bottom has hardened , use a disk sander to feather the edges of the cloth at the keel line and near the spray rail .

Before the resin has hardened , screw a one-inch mahogany keel strip along the centerline .

2
[ verb ] make fit

Synonyms

season

Examples

"This trip will season even the hardiest traveller"

Related terms

toughen

3
[ verb ] (metallurgy) harden by reheating and cooling in oil

Synonyms

temper

Examples

"temper steel"

Related terms

modify temper

4
[ verb ] make hard or harder

Synonyms

indurate

Examples

"The cold hardened the butter"

5
[ noun ] Last name, frequency rank in the U.S. is 1123
6
[ verb ] cause to accept or become hardened to; habituate

Synonyms

inure indurate

Examples

"He was inured to the cold"

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