The Collaborative International Dictionary of English v.0.48:

Rebec \Re"bec\ (r[=e]"b[e^]k), n. [F., fr. It. ribeca, ribeba,
   fr. Ar. rab[=a]b a musical instrument of a round form.]
   1. (Mus.) An instrument formerly used which somewhat
      resembled the violin, having three strings, and being
      played with a bow. [Written also rebeck.] --Milton.
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            He turn'd his rebec to a mournful note. --Drayton.
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   2. A contemptuous term applied to an old woman. [Obs.]
      --Chaucer.
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