The Collaborative International Dictionary
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.
Douglas Harper's Etymology Dictionary
1690s, from Latin apodyterium "undressing room" (in a bath house), from Greek apodyterion "undressing room," from apodyein "to put off, undress," from apo- "off" (see apo-) + dyein "to put on, enter, go in."
Wiktionary
n. (context architecture historical English) The apartment at the entrance of the baths, or in the palestra, for getting undressed.
Wikipedia
In ancient Rome, the apodyterium (from "undressing room") was the primary entry in the public baths, composed of a large changing room with cubicles or shelves where citizens could store clothing and other belongings while bathing. Privately owned slaves, or one hired at the baths, called a capsarius, would look after belongings while citizens enjoyed the pleasures of the baths. A contemporary Roman schoolbook quotes a wealthy young Roman schoolboy who entered the baths, leaving his slave behind in the apodyterium: "Do not fall asleep, on account of the thieves." (''ne addormias propter fures, ''CGL 3.651.10)
This was used in the 2009 Scripps National Spelling Bee.
Usage examples of "apodyterium".
She led the way down the stairs to the apodyterium, where waited a throng of noblewomen, banned from the baths until their princess might finish her toilet.
They now entered a somewhat spacious chamber, which served for the purposes of the apodyterium (that is, a place where the bathers prepared themselves for their luxurious ablutions).