WOAD, a herbaceous plant, known botanically as Isatis tinctoria (family Cruciferae), which occurs sporadically in Eng land in fields, on banks and chalk-pits. The erect branched stem, I to 3 ft. in height, bears sessile leaves and terminal clusters of small yellow flowers; the brown pendulous pods are in. long. The ancient Britons stained themselves with this plant. It is still cultivated in Lincolnshire.