WordReference Random House Unabridged Dictionary of American English © 2024case•hard•en (kās′här′dn),USA pronunciation v.t. - Metallurgyto make the outside surface of (an alloy having an iron base) hard by carburizing and heat treatment, leaving the interior tough and ductile.
- to harden in spirit so as to render insensible or insensitive to external impressions or influences;
make callous.
Collins Concise English Dictionary © HarperCollins Publishers::
case-harden vb (transitive)- to form a hard surface layer of high carbon content on (a steel component) by heating in a carburizing environment with subsequent quenching or heat treatment
- to harden the spirit or disposition of; make callous: experience had case-hardened the judge