harden

/ˈhɑrdən/
verb
  1. To become or make something firm, solid, or stiff.
    • The cold weather caused the ground to harden overnight.
    • The glue will harden in about an hour.
    • You need to harden the clay by baking it in a kiln.
  2. To become or make someone more severe, strict, or less sympathetic.
    • Don't let the criticism harden you against trying new things.
    • The teacher hardened her rules after the students misbehaved.
    • Years of disappointment hardened his heart.
  3. To become or make something stronger or more resistant to damage.
    • Regular exercise helps harden your bones.
    • They hardened the steel to make it last longer.
    • The company hardened its computer system against hackers.
Antonyms
What does "harden" mean? | whatsthatwordmean | whatsthatwordmean