noun

• A private chapel or prayer room.
• A Roman Catholic chapel; a building for public or private worship that is not a parish church.
• (specifically) A Catholic church belonging to the Oratory of Saint Philip Neri.
• The art of public speaking, especially in a formal, expressive, or forceful manner.
• Eloquence; the quality of artistry and persuasiveness in speech or writing.
• (Roman Catholicism) The Oratory of Saint Philip Neri, a society of priests and lay brothers founded in 1575.
• Alternative letter-case form of oratory: a church belonging to the Oratory. [A private chapel or prayer room.]