harden
🇺🇸
/ˈhɑːrdn/
🇬🇧
/ˈhɑːdn/
to become or make something firm or solid
The clay will harden when it dries.
to become or make something more serious or severe
His face began to harden with anger.
to become or make someone more determined
The challenge will harden your determination to succeed.
to make someone less kind or sensitive
Prison life can harden a person's heart.