\Or`a*to"ri*o\, n. [It., fr. L. oratorius belonging to
praying. See {Orator}, and cf. {Oratory}.]
1. (Mus.) A more or less dramatic text or poem, founded on
   some Scripture nerrative, or great divine event,
   elaborately set to music, in recitative, arias, grand
   choruses, etc., to be sung with an orchestral
   accompaniment, but without action, scenery, or costume,
   although the oratorio grew out of the Mysteries and the
   Miracle and Passion plays, which were acted.
Note: There are instances of secular and mythological
      subjects treated in the form of the oratorios, and
      called oratorios by their composers; as Haydn's
      ``Seasons,'' Handel's ``Semele,'' etc.
2. Performance or rendering of such a composition.