Lewis & Short

sūdātĭo, ōnis, f. [sudo].

  1. I. Lit., a sweating, perspiration, sudation (post-Aug.): multa, Sen. Ep. 86, 5.
    Plur., Cels. 3, 2 med.
  2. * II. Transf., in concr., a sweatingroom, sudatory: concamerata, Vitr. 5, 11 med.