onychodystrophy

[ŏn′ĭ-kō-dĭstrə-fē]
n.
  1. Dystrophic changes in fingernails or toenails, such as malformation or discoloration, occurring as a congenital defect or due to illness or injury.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.