The Collaborative International Dictionary of English v.0.48:

Oratory \Or"a*to*ry\, n.; pl. Oratories. [OE. oratorie, fr. L.
   oratorium, fr. oratorius of praying, of an orator: cf. F.
   oratoire. See Orator, Oral, and cf. Oratorio.]
   A place of orisons, or prayer; especially, a chapel or small
   room set apart for private devotions.
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         An oratory [temple] . . . in worship of Dian.
                                                  --Chaucer.
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         Do not omit thy prayers for want of a good oratory, or
         place to pray in.                        --Jer. Taylor.
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   Fathers of the Oratory (R. C. Ch.), a society of priests
      founded by St. Philip Neri, living in community, and not
      bound by a special vow. The members are called also
      oratorians.
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