harden

B1 · Intermediate

v. to make something firm or solid.

v. to cause a substance to become rigid or resistant to pressure.

“The cold weather will harden the ground, making it difficult to dig.”

“Special chemicals are added to the mixture to harden the plastic during the manufacturing process.”

B2 · Upper Intermediate

v. to become more tough or less easily upset by difficult things.

v. to become emotionally callous, resilient, or less susceptible to sympathy or pain.

“Years of working in the emergency room had hardened his heart to suffering.”

“The soldiers had been hardened by months of combat, showing little emotion even in dire circumstances.”

C1 · Advanced Computing Technical

v. to make a computer system or website safer against hackers.

v. to reduce a system's vulnerability by reducing its attack surface and layering technical protections.

“The IT team needs to harden the server before we launch the new site.”

“System administrators must harden the operating system by disabling unnecessary services and enforcing strict password policies.”