Lewis & Short

in-dūresco, rŭi, 3, v. inch. n., to become hard, to harden (cf. percallesco; postAug.).

  1. I. Lit.: si vetus condyloma jam induruit, Cels. 6, 18, 8: grana, Col. 2, 20, 2.
  2. II. Trop.: miles induruerat pro Vitellio, had become unalterably firm in his attachment to Vitellius, Tac. H. 3, 61: in pravum, to become hardened in, Quint. 1, 3, 12.