Crystal violet or Gentian violet (also known as Methyl Violet 10B, hexamethyl pararosaniline

Pararosaniline

Pararosaniline, Basic Red 9, or C.I. 42500 is a magenta dye having chemical formula 19183. It is one of the four components of basic fuchsine. Pararosaniline, which is sold as a single dye, may make the best Schiff's reagent...

 chloride, or pyoctanin(e)) is a triarylmethane

Triphenylmethane

Triphenylmethane, or triphenyl methane, is the hydrocarbon with the formula 3CH. This colorless solid is soluble in nonpolar organic solvents and not in water. Triphenylmethane has the basic skeleton of many synthetic dyes called triarylmethane dyes, many of them are pH indicators, and some display...

 dye. The dye is used as a histological stain and in Gram’s method

Gram staining

Gram staining is a method of differentiating bacterial species into two large groups ....

 of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelmintic

Anthelmintic

Anthelmintics or antihelminthics are drugs that expel parasitic worms from the body, by either stunning or killing them. They may also be called vermifuges or vermicides .-Pharmaceutical classes:...

 properties and was formerly important as a topical

Topical

In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...

 antiseptic. The medical use of the dye has been largely superseded by more modern drugs, although it is still listed by the World Health Organization

World Health Organization

The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

.

The name "gentian violet" was originally used for a mixture of methyl pararosaniline dyes (methyl violet

Methyl violet

Methyl violet is a family of organic compounds that are mainly used as dyes. Depending on the amount of attached methyl groups, the color of the dye can be altered. Its main use is as a purple dye for textiles and to give deep violet colors in paint and ink...

) but is now often considered a synonym for crystal violet.