The process by which something hardens. / That which hardens, such as a material used for converting the surface of iron into steel.

present participle of harden

(intransitive) To become hard (tough, resistant to pressure). / (transitive, ergative) To make something hard or harder (tough, resistant to pressure). / (transitive, figuratively) To strengthen.

Alternative form of hurden (“coarse linen”)

A surname.

Third-person singular simple present indicative form of harden someone's heart

(metallurgy) The repeated plastic deformation of a material, causing a permanent distortion of its crystal structure, and an increase in its strength

(metallurgy) The process of imparting greater hardness to the surface of a piece of metal.

(metallurgy) Metal that is harder at its surface, due to a case hardening process.

simple past tense and past participle of case harden