harden

verbs

become hard or harder
"The wax hardened"
harden, indurate
is derived from
hardening
antonym
soften
make hard or harder
"The cold hardened the butter"
harden, indurate
is derived from
hardening
antonym
soften
harden by reheating and cooling in oil
"temper steel"
harden, temper
make fit
"This trip will season even the hardiest traveller"
harden, season
cause to accept or become hardened to; habituate
"He was inured to the cold"
harden, indurate, inure