1. The part of a theater designed to accommodate an audience: The people wanting to see the movie sat in the auditorium and were told not to disturb others by talking loudly or eating chips.
2. A large room to accommodate an audience in a building: The public school had a large auditorium for the parents to sit and watch the play put on by the students.
3. A large building for public meetings or performances: The city had a large public auditorium for authors to present and read passages from their books, for artists to present their paintings, or for concerts to take place.
4. Etymology: from Latin auditorium, "lecture room"; literally, "a place where something is heard"; neuter of auditorius, "of" or "for hearing"; from auditor, "a listener"; from audire, "to hear".

An auditorium can also describe an entire theater, and has been in use as a word since the 18th century, although there were other words with the same meaning before that.