induration (n.)

late 14c., "a hardening or congealing" (of body parts, alchemical materials), from Old French induracion "hardness, obstinacy" (14c.) or directly from Medieval Latin indurationem (nominative induratio) "hardness (especially of the heart)," noun of action from past participle stem of Latin indurare "to make hard, harden" (see endure).