Woad Blue

Isatis tinctoria

Isatis tinctoria, also called woad, dyer's woad, dyer's-weed, or glastum, is a flowering plant in the family Brassicaceae with a documented history of use as a blue dye and medicinal plant. The double use of woad is seen in its name: the term Isatis is linked to its ancient use to treat wounds; the term tinctoria references its use as a dye. It is occasionally known as Asp of Jerusalem. Woad is also the name of a blue dye produced from the leaves of the plant. Woad is native to the steppe and desert zones of the Caucasus, Central Asia to Eastern Siberia and Western Asia but is now also found in South-Eastern and Central Europe and western North America.

Blue

Blue is one of the three primary colours in the RGB (additive) colour model, as well as in the RYB colour model. It lies between violet and cyan on the spectrum of visible light. The term blue generally describes colours perceived by humans observing light with a dominant wavelength between approximately 450 and 495 nanometres. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called the Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective.

woad

Noun

1. The plant Isatis tinctoria.
2. The blue vat dye made from the leaves of the plant through partial drying and fermentation.

Verb

1. To plant or cultivate woad.
2. To dye with woad.

blue

Adjective

1. Of a blue hue.
2. Depressed, melancholic, sad.

Noun

1. The colour of the clear sky or the deep sea; the colour midway between green and violet in the visible spectrum and one of the primary additive colours.
2. Anything coloured blue, especially to distinguish it from similar objects differing only in colour.