rose bengal

[rōz bĕn-gôl, bĕng-, bĕngəl, bĕng-]
n.
  1. A bluish-red dye used as a stain for bacteria, as a stain in the diagnosis of keratitis sicca, and in tests of liver function.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.