AUDITORIUM
auditorium
(noun) the area of a theater or concert hall where the audience sits
Source: WordNet® 3.1
Etymology
Noun
auditorium (plural auditoriums or auditoria)
A large room for public meetings or performances.
(in a theater, etc.) The space where the audience is located.
Source: Wiktionary
Au`di*to"ri*um, n. Etym: [L. See Auditory, n.]
Definition: The part of a church, theater, or other public building,
assigned to the audience.
Note: In ancient churches the auditorium was the nave, where hearers
stood to be instructed; in monasteries it was an apartment for the
reception of strangers.
Source: Webster’s Unabridged Dictionary 1913 Edition