Gentian blue

What is Gentian blue?

Gentian blue definition and meaning on Dictionary terms:
any of several plants of the genera Gentiana, Gentianella, and Gentianopsis, having usually blue, or sometimes yellow, white, or red, flowers, as the fringed gentian of North America, or Gentiana lutea, of Europe.Compare gentian family.
any of various plants resembling the gentian.
the root of G. lutea, or a preparation of it, used as a tonic.