gentian violet

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A dye used in microscopy as a biological stain and in medicine as a bactericide, fungicide, and anthelmintic.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chemistry Also known as crystal violet, a chemical dye used in the Gram stain test, and is also a fungicide. Chemically: hexamethyl pararosaniline chloride, C25H30ClN3
• noun A violet colour similar to the gentian flower.
• adjective Having a violet colour similar to the gentian flower.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a green crystal (violet in water) used as a dye or stain or bactericide or fungicide or anthelmintic or burn treatment