Azuline is a coal-tar blue dye that became popular for colouring silk in 1861. It was one of the first synthetic dyes. The name was a combination of "azure" and "aniline". A variant of the name was "Azurine". The word was introduced as a colour term about the same time as "mauve" and "magenta", but it has not survived in the English language. Chemists at first did not know the structure of the molecules in the coal tar dyes including azuline. Use of azuline was superseded by aniline blue.