1. a small chapel, especially for private worship.
2. (in the Roman Catholic Church) a society of priests without vows, especially the Oratory of St. Philip Neri founded in 1564.
Word OriginMiddle English: from Anglo-Norman French oratorie, from ecclesiastical Latin oratorium, based on Latin orare ‘pray, speak’; sense 2 is from Congregation of the Fathers of the Oratory.