oratorio.
1. Strictly, a mus. setting of a religious lib. for solo singers, ch., and orch., in dramatic form but usually perf. without scenery or costumes in concert-hall or church. The form originated in plays given in the Oratory of S. Philip Neri, Rome, in the mid-16th cent., the mus. form developing c.1600. The first oratorio was Cavalieri's La rappresentazione di anima e di corpo (The Representation of Soul and Body), a morality set to music and perf. in costume. Later oratorios, in concert-form, were written by Carissimi, A. Scarlatti, Schütz, Handel (esp. Messiah, the most popular of all oratorios), Haydn, Spohr, Beethoven, and Mendelssohn (Elijah). Elgar wrote 3 oratorios (but The Dream of Gerontius is not an oratorio).

2. The term is also applied to works similar to these cited above but on a non-religious subject, e.g. Handel's Semele, Tippett's A Child of our Time. Stravinsky's Oedipus Rex is described as an opera-oratorio.

or·a·to·ri·o / ˌôrəˈtôrēˌō; ˌär-/ • n. (pl. -os) a large-scale musical work for orchestra and voices, typically a narrative on a religious theme, performed without the use of costumes, scenery, or action.Well-known examples include Bach's Christmas Oratorio, Handel's Messiah, and Haydn's The Creation.

oratorio XVIII. — It. — ecclL. ōrātōrium ORATORY1; so named from the musical performances held in the church of the Oratory of St. Philip Neri in Rome from the latter part of XVI.

oratorio Form of sacred musical composition for solo voices, chorus, and orchestra. The first of these compositions were presented in oratories (chapels) in 17th-century Italy. Outstanding examples are Handel's Messiah (1742) and Elgar's Dream of Gerontius (1900).

oratorio a large-scale, usually narrative musical work for orchestra and voices, typically on a sacred theme, performed without costume, scenery, or action. The form arose in the early 17th century, from the services of the Oratory.