apodyterium

from The Collaborative International Dictionary of English v.0.48

Apodyterium \A*pod`y*te"ri*um\, n. [L., fr. Gr. ?, fr. ? to
   strip one's self.] (Anc. Arch.)
   The apartment at the entrance of the baths, or in the
   palestra, where one stripped; a dressing room.
   [1913 Webster]