/awr'euh tawr"ee oh', -tohr"-, or'-/ , n. , pl. oratorios .
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.
[ 1625-35; oratorium ORATORY 2 ; so named from the musical services in the church of the Oratory of St. Philip Neri in Rome ]