an extended musical composition with a text more or less dramatic in character and usually based upon a religious theme, for solo voices, chorus, and orchestra, and performed without action, costume, or scenery.
Origin: 1625–35; < It: small chapel < LL ōrātōriumoratory2; so named from the musical services in the church of the Oratory of St. Philip Neri in Rome
or·a·to·ri·o (ôr'ə-tôr'ē-ō', -tōr'-, ŏr'-) n.
pl.or·a·to·ri·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.]