The Collaborative International Dictionary of English v.0.48:

Sleeper \Sleep"er\, n.
   1. One who sleeps; a slumberer; hence, a drone, or lazy
      person.
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   2. That which lies dormant, as a law. [Obs.] --Bacon.
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   3. A sleeping car. [Colloq. U.S.]
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   4. (Zool.) An animal that hibernates, as the bear.
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   5. (Zool.)
      (a) A large fresh-water gobioid fish (Eleotris
          dormatrix).
      (b) A nurse shark. See under Nurse.
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