leptocyte

[lĕptə-sīt′]
n.
  1. An abnormally thin or flattened red blood cell having a central rounded pigmented area, a middle pigmentless zone, and a pigmented edge.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.