woad (dyerswoad) Biennial or perennial herb once grown as a source of blue dye. It was probably introduced by the early Britons to dye clothing and paint their bodies. A native of Eurasia, it bears small four-petalled, yellow flowers. Height: 90cm (3ft). Family Brassicaceae/Cruciferae; species Isatis tinctoria.

woad a yellow-flowered European plant, formerly widely grown in Britain as a source of blue dye. It is often referred to allusively as typifying an early and uncivilized era in which the skin was patterned with woad.

woad blue dye-stuff obtained from the plant Isatis tinctoria. OE. wād = MLG., MDu. wēt, (also mod.) weede, OHG. weit (G. waid):- WGmc. *waida-.