indurate (v.)

1590s (transitive) "make hard;" 1620s (intransitive) "grow harder," from Latin induratus, past participle of indurare "to make hard, harden," from in- (from PIE root *en "in") + durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast." Related: Indurated.

"hardened, made hard," early 15c., from Latin induratus, past participle of indurare "to make hard, harden," from in- (from PIE root *en "in") + durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast."