Woad (?), n. [OE. wod, AS. wad; akin to D. weede, G. waid, OHG. weit, Dan. vaid, veid, Sw. veide, L. vitrum.] [Written also wad, and wade.]
1. Bot.
An herbaceous cruciferous plant (Isatis tinctoria). It was formerly cultivated for the blue coloring matter derived from its leaves.
2.
A blue dyestuff, or coloring matter, consisting of the powdered and fermented leaves of the Isatis tinctoria. It is now superseded by indigo, but is somewhat used with indigo as a ferment in dyeing.
Their bodies . . . painted with woad in sundry figures.
Milton.
Wild woad Bot., the weld (Reseda luteola). See Weld. -- Woad mill, a mill grinding and preparing woad.
© Webster 1913.