The Collaborative International Dictionary
Obduration
Obduration \Ob"du*ra"tion\, n. [L. obduratio.] A hardening of the heart; hardness of heart. [Obs.]
Douglas Harper's Etymology Dictionary
obduration
c.1400, "hard-heartedness," from Latin obdurationem (nominative obduratio), noun of state from past participle stem of obdurare (see obdurate).
Wiktionary
obduration
n. (context obsolete English) A hardening of the heart; hardness of heart.