congenital megacolon

n.
  1. Congenital dilation and hypertrophy of a segment of the colon due to an absence or marked reduction in the number of motor neurons innervating its muscular coat, resulting in extreme constipation and, if untreated, growth retardation.Hirschsprung's disease
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.