Lewis & Short

rĕformātio, ōnis, f. [reformo], a transformation (very rare).

  1. I. Lit., of a metamorphosis into an ass, App. M. 3, p. 140, 3; cf. id. ib. 11, p. 263, 19.
  2. II. Trop. and pregn., a reformation: morum, Sen. Ep. 58, 26.