The Collaborative International Dictionary of English v.0.48:

Kipper \Kip"per\, n. [D. kippen to hatch, snatch, seize. Cf.
   Kipe.]
   1. (Zool.) A salmon after spawning.
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   2. A salmon split open, salted, and dried or smoked; -- so
      called because salmon after spawning were usually so
      cured, not being good when fresh. [Scot.]
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   Kipper time, the season in which fishing for salmon is
      forbidden. [Eng. & Scot.]
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