What is a receiving room?

"In architectural acoustical measurements, the room in which the sound transmitted from the source room is measured."

http://www.eckel.ca/support/acoustics-primer/acoustic-glossary.html

Another definition exists, as noted in the attached link:

"The receiving room is one of the most useful rooms during parties and other special occasions. It is the room used to receive guest and it is where most of the interaction between the hosts and guests happen... it is a room designed to house visitors temporarily during their stay under your roof"

[phantasmsecrets.com/receiving-room-living-room-furniture] - Link no longer valid