[ keys-hahr-dn ]
/ ˈkeɪsˌhɑr dn /
verb (used with object)
Metallurgy. to 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.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for caseharden
I have a peculiar kind of steel which I cannot harden by fire and water, neither will it caseharden by prussiate of potash.