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chocolate cyst

[chô′kə-lĭt, chôk′lĭt, chŏk′-]
n.
  1. A cyst of the ovary containing old brown blood.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.