Woad \Woad\, n. [OE. wod, AS. w[=a]d; 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 It is now superseded by indigo, but is somewhat used with indigo as a ferment in dyeing.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.

Source: Webster's Revised Unabridged Dictionary (1913)