- a European plant, Isatis tinctoria, of the mustard family, formerly cultivated for a blue dye extracted from its leaves.
- the dye extracted from this plant.
O.E. wad, from P.Gmc. *waido- (cf. Dan. vaid, O.Fris. wed, M.Du. wede, Du. wede, O.H.G. weit, Ger. Waid "woad"), probably cognate with L. vitrium "glass" (see vitreous). Old type of blue dye processed from plant leaves, since superseded by indigo. Fr. guède, It. guado are Gmc. loan-words.
"My dress is all wrong, of far too fine a weave, and the blue is too bright, dyed with woad or not."
- Connie Willis, Doomsday Book