Definition of "prothyrum" [prothyrum]

• In Greco-Rom. archæol., the front door or the vestibule or porch of entrance to any building. (noun)

The Century Dictionary (Public Domain)

• "The first of these names is derived from the mosaic pavement in the prothyrum, in which the objects mentioned are represented; while a medallion picture in the atrium, with heads of"
• "It offers to the eye, successively, the doorway, the prothyrum, the atrium, with its impluvium, the Ionic peristyle, and the garden wall, with Vesuvius in the distance."
• "On the left of the prothyrum is an apartment with two doors, one opening on a wooden staircase leading to an upper floor, the other forming the entry to a room next the street, with a window like that described in the other room next the prothyrum."