melanosis coli

[kōlī]
n.
  1. Melanosis of the mucosa of the large intestine, due to accumulation of pigment within macrophages in the lamina propria mucosae.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.