Lewis & Short

ob-dūro, āvi, ātum, 1, v. a. and n.

  1. I. Act., to harden, render hard (only postclass.); in the trop. signif.: obdurare se contra manifestam veritatem, Lact. 1, 1, 23: obdurata patientia, Nazar. Pan. ad Const. 13: obdurata nequitia, Cod. Just. 10, 19, 2: obdurata verecundia, Capitol. Pert. 9.
    Esp., to harden the heart against God (eccl. Lat.): obdurare corda, Vulg. Heb. 3, 8; id. Psa. 94, 8; id. Deut. 15, 7.
    Pass.: ut non obduretur quis vestrum, Vulg. Heb. 3, 13.
  2. II. Neutr., to be hard or hardened; only trop., to hold out, persist, endure: pernegabo atque obdurabo, Plaut. As. 2, 2, 56: persta, atque obdura, Hor. S. 2, 5, 39; Cat. 8, 11: perfer et obdura, Ov. Tr. 5, 11, 7.
    Impers. pass.: quare obduretur hoc triduum, * Cic. Att. 12, 3.