n., pl., -os.
A musical composition for voices and orchestra, telling a sacred story without costumes, scenery, or dramatic action.
[Italian, after Oratorio, the Oratory of Saint Philip Neri at Rome, where famous musical services were held in the 16th century.]
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.