Old English wad "woad," also the blue dye made from its leaves, from Proto-Germanic *waido- (cognates: Danish vaid, Old Frisian wed, Middle Dutch wede, Dutch wede, Old High German weit, German Waid "woad"), perhaps cognate with Latin vitrium "glass" (see vitreous). Formerly much cultivated; since superseded by indigo. French guède, Italian guado are Germanic loan-words.
1. A blue dyestuff can be obtained from the woad plant.
2. Old World genus of annual to perennial herbs: woad.