harden

verb

1.
become hard or harder
indurate
Antonym:
soften
Derived from:
hardening
2.
make hard or harder
indurate
Antonym:
soften
Derived from:
hardening
3.
harden by reheating and cooling in oil
tempered temper
4.
make healthy
season
5.
cause to accept or become hardened to; habituate
indurate inure