anteroom

noun

1. A room before, or forming an entrance to, another; a waiting room.

   “[T]his was one of the anterooms off the main throneroom in which the king was accustomed to hold court with his entire retinue.”

   “Several antique games, such as a skiddles table, occupy an upstairs anteroom.”

   “These stories take on pulp fiction’s sensational subjects. But episodes of murder, suicide and adultery turn out to be just anterooms to an echo chamber filled with subtle and far-reaching thematic reverberations.”