The Collaborative International Dictionary of English v.0.48:

Rookery \Rook"er*y\, n.; pl. Rookeries.
   1. The breeding place of a colony of rooks; also, the birds
      themselves. --Tennyson.
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   2. A breeding place of other gregarious birds, as of herons,
      penguins, etc.
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   3. The breeding ground of seals, esp. of the fur seals.
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   4. A dilapidated building with many rooms and occupants; a
      cluster of dilapidated or mean buildings.
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   5. A brothel. [Low]
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